diff --git a/backend/package-lock.json b/backend/package-lock.json
index 69a370d9..207f0f50 100644
--- a/backend/package-lock.json
+++ b/backend/package-lock.json
@@ -11,6 +11,7 @@
       "dependencies": {
         "@fastify/cors": "^11.1.0",
         "@fastify/jwt": "^10.0.0",
+        "@fastify/multipart": "^9.2.1",
         "@prisma/client": "^6.17.0",
         "@types/form-data": "^2.2.1",
         "axios": "^1.12.2",
@@ -507,6 +508,12 @@
         "fast-uri": "^3.0.0"
       }
     },
+    "node_modules/@fastify/busboy": {
+      "version": "3.2.0",
+      "resolved": "https://registry.npmmirror.com/@fastify/busboy/-/busboy-3.2.0.tgz",
+      "integrity": "sha512-m9FVDXU3GT2ITSe0UaMA5rU3QkfC/UXtCU8y0gSN/GugTqtVldOBWIB5V6V3sbmenVZUIpU6f+mPEO2+m5iTaA==",
+      "license": "MIT"
+    },
     "node_modules/@fastify/cors": {
       "version": "11.1.0",
       "resolved": "https://registry.npmmirror.com/@fastify/cors/-/cors-11.1.0.tgz",
@@ -527,6 +534,22 @@
         "toad-cache": "^3.7.0"
       }
     },
+    "node_modules/@fastify/deepmerge": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmmirror.com/@fastify/deepmerge/-/deepmerge-3.1.0.tgz",
+      "integrity": "sha512-lCVONBQINyNhM6LLezB6+2afusgEYR4G8xenMsfe+AT+iZ7Ca6upM5Ha8UkZuYSnuMw3GWl/BiPXnLMi/gSxuQ==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "MIT"
+    },
     "node_modules/@fastify/error": {
       "version": "4.2.0",
       "resolved": "https://registry.npmmirror.com/@fastify/error/-/error-4.2.0.tgz",
@@ -620,6 +643,29 @@
         "dequal": "^2.0.3"
       }
     },
+    "node_modules/@fastify/multipart": {
+      "version": "9.2.1",
+      "resolved": "https://registry.npmmirror.com/@fastify/multipart/-/multipart-9.2.1.tgz",
+      "integrity": "sha512-U4221XDMfzCUtfzsyV1/PkR4MNgKI0158vUUyn/oF2Tl6RxMc+N7XYLr5fZXQiEC+Fmw5zFaTjxsTGTgtDtK+g==",
+      "funding": [
+        {
+          "type": "github",
+          "url": "https://github.com/sponsors/fastify"
+        },
+        {
+          "type": "opencollective",
+          "url": "https://opencollective.com/fastify"
+        }
+      ],
+      "license": "MIT",
+      "dependencies": {
+        "@fastify/busboy": "^3.0.0",
+        "@fastify/deepmerge": "^3.0.0",
+        "@fastify/error": "^4.0.0",
+        "fastify-plugin": "^5.0.0",
+        "secure-json-parse": "^4.0.0"
+      }
+    },
     "node_modules/@fastify/proxy-addr": {
       "version": "5.1.0",
       "resolved": "https://registry.npmmirror.com/@fastify/proxy-addr/-/proxy-addr-5.1.0.tgz",
diff --git a/backend/package.json b/backend/package.json
index d89ce1c5..9e0bd6ff 100644
--- a/backend/package.json
+++ b/backend/package.json
@@ -24,6 +24,7 @@
   "dependencies": {
     "@fastify/cors": "^11.1.0",
     "@fastify/jwt": "^10.0.0",
+    "@fastify/multipart": "^9.2.1",
     "@prisma/client": "^6.17.0",
     "@types/form-data": "^2.2.1",
     "axios": "^1.12.2",
diff --git a/backend/src/controllers/documentController.ts b/backend/src/controllers/documentController.ts
new file mode 100644
index 00000000..9af1a68b
--- /dev/null
+++ b/backend/src/controllers/documentController.ts
@@ -0,0 +1,246 @@
+import type { FastifyRequest, FastifyReply } from 'fastify';
+import * as documentService from '../services/documentService.js';
+
+// Mock用户ID（实际应从JWT token中获取）
+const MOCK_USER_ID = 'user-mock-001';
+
+/**
+ * 上传文档
+ */
+export async function uploadDocument(
+  request: FastifyRequest<{
+    Params: {
+      kbId: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { kbId } = request.params;
+
+    // 获取上传的文件
+    const data = await request.file();
+
+    if (!data) {
+      return reply.status(400).send({
+        success: false,
+        message: 'No file uploaded',
+      });
+    }
+
+    const file = await data.toBuffer();
+    const filename = data.filename;
+    const fileType = data.mimetype;
+    const fileSizeBytes = file.length;
+
+    // 文件大小限制（10MB）
+    if (fileSizeBytes > 10 * 1024 * 1024) {
+      return reply.status(400).send({
+        success: false,
+        message: 'File size exceeds 10MB limit',
+      });
+    }
+
+    // 文件类型限制
+    const allowedTypes = [
+      'application/pdf',
+      'application/msword',
+      'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
+      'text/plain',
+      'text/markdown',
+    ];
+
+    if (!allowedTypes.includes(fileType)) {
+      return reply.status(400).send({
+        success: false,
+        message: 'File type not supported. Allowed: PDF, DOC, DOCX, TXT, MD',
+      });
+    }
+
+    // 上传文档（这里fileUrl暂时为空，实际应该上传到对象存储）
+    const document = await documentService.uploadDocument(
+      MOCK_USER_ID,
+      kbId,
+      file,
+      filename,
+      fileType,
+      fileSizeBytes,
+      '' // fileUrl - 可以上传到OSS后填入
+    );
+
+    return reply.status(201).send({
+      success: true,
+      data: document,
+    });
+  } catch (error: any) {
+    console.error('Failed to upload document:', error);
+
+    if (error.message.includes('not found') || error.message.includes('access denied')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    if (error.message.includes('limit exceeded')) {
+      return reply.status(400).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to upload document',
+    });
+  }
+}
+
+/**
+ * 获取文档列表
+ */
+export async function getDocuments(
+  request: FastifyRequest<{
+    Params: {
+      kbId: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { kbId } = request.params;
+
+    const documents = await documentService.getDocuments(MOCK_USER_ID, kbId);
+
+    return reply.send({
+      success: true,
+      data: documents,
+    });
+  } catch (error: any) {
+    console.error('Failed to get documents:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to get documents',
+    });
+  }
+}
+
+/**
+ * 获取文档详情
+ */
+export async function getDocumentById(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    const document = await documentService.getDocumentById(MOCK_USER_ID, id);
+
+    return reply.send({
+      success: true,
+      data: document,
+    });
+  } catch (error: any) {
+    console.error('Failed to get document:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to get document',
+    });
+  }
+}
+
+/**
+ * 删除文档
+ */
+export async function deleteDocument(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    await documentService.deleteDocument(MOCK_USER_ID, id);
+
+    return reply.send({
+      success: true,
+      message: 'Document deleted successfully',
+    });
+  } catch (error: any) {
+    console.error('Failed to delete document:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to delete document',
+    });
+  }
+}
+
+/**
+ * 重新处理文档
+ */
+export async function reprocessDocument(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    await documentService.reprocessDocument(MOCK_USER_ID, id);
+
+    return reply.send({
+      success: true,
+      message: 'Document reprocessing started',
+    });
+  } catch (error: any) {
+    console.error('Failed to reprocess document:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to reprocess document',
+    });
+  }
+}
+
diff --git a/backend/src/controllers/knowledgeBaseController.ts b/backend/src/controllers/knowledgeBaseController.ts
new file mode 100644
index 00000000..4d3f7a01
--- /dev/null
+++ b/backend/src/controllers/knowledgeBaseController.ts
@@ -0,0 +1,291 @@
+import type { FastifyRequest, FastifyReply } from 'fastify';
+import * as knowledgeBaseService from '../services/knowledgeBaseService.js';
+
+// Mock用户ID（实际应从JWT token中获取）
+const MOCK_USER_ID = 'user-mock-001';
+
+/**
+ * 创建知识库
+ */
+export async function createKnowledgeBase(
+  request: FastifyRequest<{
+    Body: {
+      name: string;
+      description?: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { name, description } = request.body;
+
+    if (!name || name.trim().length === 0) {
+      return reply.status(400).send({
+        success: false,
+        message: 'Knowledge base name is required',
+      });
+    }
+
+    const knowledgeBase = await knowledgeBaseService.createKnowledgeBase(
+      MOCK_USER_ID,
+      name,
+      description
+    );
+
+    return reply.status(201).send({
+      success: true,
+      data: knowledgeBase,
+    });
+  } catch (error: any) {
+    console.error('Failed to create knowledge base:', error);
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to create knowledge base',
+    });
+  }
+}
+
+/**
+ * 获取知识库列表
+ */
+export async function getKnowledgeBases(
+  _request: FastifyRequest,
+  reply: FastifyReply
+) {
+  try {
+    const knowledgeBases = await knowledgeBaseService.getKnowledgeBases(
+      MOCK_USER_ID
+    );
+
+    return reply.send({
+      success: true,
+      data: knowledgeBases,
+    });
+  } catch (error: any) {
+    console.error('Failed to get knowledge bases:', error);
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to get knowledge bases',
+    });
+  }
+}
+
+/**
+ * 获取知识库详情
+ */
+export async function getKnowledgeBaseById(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    const knowledgeBase = await knowledgeBaseService.getKnowledgeBaseById(
+      MOCK_USER_ID,
+      id
+    );
+
+    return reply.send({
+      success: true,
+      data: knowledgeBase,
+    });
+  } catch (error: any) {
+    console.error('Failed to get knowledge base:', error);
+    
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to get knowledge base',
+    });
+  }
+}
+
+/**
+ * 更新知识库
+ */
+export async function updateKnowledgeBase(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+    Body: {
+      name?: string;
+      description?: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+    const updateData = request.body;
+
+    const knowledgeBase = await knowledgeBaseService.updateKnowledgeBase(
+      MOCK_USER_ID,
+      id,
+      updateData
+    );
+
+    return reply.send({
+      success: true,
+      data: knowledgeBase,
+    });
+  } catch (error: any) {
+    console.error('Failed to update knowledge base:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to update knowledge base',
+    });
+  }
+}
+
+/**
+ * 删除知识库
+ */
+export async function deleteKnowledgeBase(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    await knowledgeBaseService.deleteKnowledgeBase(MOCK_USER_ID, id);
+
+    return reply.send({
+      success: true,
+      message: 'Knowledge base deleted successfully',
+    });
+  } catch (error: any) {
+    console.error('Failed to delete knowledge base:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to delete knowledge base',
+    });
+  }
+}
+
+/**
+ * 检索知识库
+ */
+export async function searchKnowledgeBase(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+    Querystring: {
+      query: string;
+      top_k?: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+    const { query, top_k } = request.query;
+
+    if (!query || query.trim().length === 0) {
+      return reply.status(400).send({
+        success: false,
+        message: 'Query parameter is required',
+      });
+    }
+
+    const topK = top_k ? parseInt(top_k, 10) : 3;
+
+    const results = await knowledgeBaseService.searchKnowledgeBase(
+      MOCK_USER_ID,
+      id,
+      query,
+      topK
+    );
+
+    return reply.send({
+      success: true,
+      data: results,
+    });
+  } catch (error: any) {
+    console.error('Failed to search knowledge base:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to search knowledge base',
+    });
+  }
+}
+
+/**
+ * 获取知识库统计信息
+ */
+export async function getKnowledgeBaseStats(
+  request: FastifyRequest<{
+    Params: {
+      id: string;
+    };
+  }>,
+  reply: FastifyReply
+) {
+  try {
+    const { id } = request.params;
+
+    const stats = await knowledgeBaseService.getKnowledgeBaseStats(
+      MOCK_USER_ID,
+      id
+    );
+
+    return reply.send({
+      success: true,
+      data: stats,
+    });
+  } catch (error: any) {
+    console.error('Failed to get knowledge base stats:', error);
+
+    if (error.message.includes('not found')) {
+      return reply.status(404).send({
+        success: false,
+        message: error.message,
+      });
+    }
+
+    return reply.status(500).send({
+      success: false,
+      message: error.message || 'Failed to get knowledge base stats',
+    });
+  }
+}
+
diff --git a/backend/src/index.ts b/backend/src/index.ts
index 6ecade4b..4b1ef2ba 100644
--- a/backend/src/index.ts
+++ b/backend/src/index.ts
@@ -1,10 +1,17 @@
 import Fastify from 'fastify';
 import cors from '@fastify/cors';
+import multipart from '@fastify/multipart';
 import { config, validateEnv } from './config/env.js';
 import { testDatabaseConnection, prisma } from './config/database.js';
 import { projectRoutes } from './routes/projects.js';
 import { agentRoutes } from './routes/agents.js';
 import { conversationRoutes } from './routes/conversations.js';
+import knowledgeBaseRoutes from './routes/knowledgeBases.js';
+
+// 全局处理BigInt序列化
+(BigInt.prototype as any).toJSON = function() {
+  return Number(this);
+};
 
 const fastify = Fastify({
   logger: {
@@ -26,6 +33,13 @@ await fastify.register(cors, {
   credentials: true,
 });
 
+// 注册文件上传插件
+await fastify.register(multipart, {
+  limits: {
+    fileSize: 10 * 1024 * 1024, // 10MB
+  },
+});
+
 // 健康检查路由
 fastify.get('/health', async () => {
   // 检查数据库连接
@@ -63,6 +77,9 @@ await fastify.register(agentRoutes, { prefix: '/api/v1' });
 // 注册对话管理路由
 await fastify.register(conversationRoutes, { prefix: '/api/v1' });
 
+// 注册知识库管理路由
+await fastify.register(knowledgeBaseRoutes, { prefix: '/api/v1' });
+
 // 启动服务器
 const start = async () => {
   try {
diff --git a/backend/src/routes/knowledgeBases.ts b/backend/src/routes/knowledgeBases.ts
new file mode 100644
index 00000000..3259d68f
--- /dev/null
+++ b/backend/src/routes/knowledgeBases.ts
@@ -0,0 +1,46 @@
+import type { FastifyInstance } from 'fastify';
+import * as knowledgeBaseController from '../controllers/knowledgeBaseController.js';
+import * as documentController from '../controllers/documentController.js';
+
+export default async function knowledgeBaseRoutes(fastify: FastifyInstance) {
+  // ==================== 知识库管理 API ====================
+
+  // 创建知识库
+  fastify.post('/knowledge-bases', knowledgeBaseController.createKnowledgeBase);
+
+  // 获取知识库列表
+  fastify.get('/knowledge-bases', knowledgeBaseController.getKnowledgeBases);
+
+  // 获取知识库详情
+  fastify.get('/knowledge-bases/:id', knowledgeBaseController.getKnowledgeBaseById);
+
+  // 更新知识库
+  fastify.put('/knowledge-bases/:id', knowledgeBaseController.updateKnowledgeBase);
+
+  // 删除知识库
+  fastify.delete('/knowledge-bases/:id', knowledgeBaseController.deleteKnowledgeBase);
+
+  // 检索知识库
+  fastify.get('/knowledge-bases/:id/search', knowledgeBaseController.searchKnowledgeBase);
+
+  // 获取知识库统计信息
+  fastify.get('/knowledge-bases/:id/stats', knowledgeBaseController.getKnowledgeBaseStats);
+
+  // ==================== 文档管理 API ====================
+
+  // 上传文档
+  fastify.post('/knowledge-bases/:kbId/documents', documentController.uploadDocument);
+
+  // 获取文档列表
+  fastify.get('/knowledge-bases/:kbId/documents', documentController.getDocuments);
+
+  // 获取文档详情
+  fastify.get('/documents/:id', documentController.getDocumentById);
+
+  // 删除文档
+  fastify.delete('/documents/:id', documentController.deleteDocument);
+
+  // 重新处理文档
+  fastify.post('/documents/:id/reprocess', documentController.reprocessDocument);
+}
+
diff --git a/backend/src/services/documentService.ts b/backend/src/services/documentService.ts
new file mode 100644
index 00000000..62a29c18
--- /dev/null
+++ b/backend/src/services/documentService.ts
@@ -0,0 +1,327 @@
+import { prisma } from '../config/database.js';
+import { difyClient } from '../clients/DifyClient.js';
+
+/**
+ * 文档服务
+ */
+
+/**
+ * 上传文档到知识库
+ */
+export async function uploadDocument(
+  userId: string,
+  kbId: string,
+  file: Buffer,
+  filename: string,
+  fileType: string,
+  fileSizeBytes: number,
+  fileUrl: string
+) {
+  // 1. 验证知识库权限
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 检查文档数量限制（每个知识库最多50个文档）
+  const documentCount = await prisma.document.count({
+    where: { kbId },
+  });
+
+  if (documentCount >= 50) {
+    throw new Error('Document limit exceeded. Maximum 50 documents per knowledge base');
+  }
+
+  // 3. 在数据库中创建文档记录（状态：uploading）
+  const document = await prisma.document.create({
+    data: {
+      kbId,
+      userId,
+      filename,
+      fileType,
+      fileSizeBytes,
+      fileUrl,
+      difyDocumentId: '', // 暂时为空，稍后更新
+      status: 'uploading',
+      progress: 0,
+    },
+  });
+
+  try {
+    // 4. 上传到Dify
+    const difyResult = await difyClient.uploadDocumentDirectly(
+      knowledgeBase.difyDatasetId,
+      file,
+      filename
+    );
+
+    // 5. 更新文档记录（更新difyDocumentId和状态）
+    const updatedDocument = await prisma.document.update({
+      where: { id: document.id },
+      data: {
+        difyDocumentId: difyResult.document.id,
+        status: difyResult.document.indexing_status,
+        progress: 50,
+      },
+    });
+
+    // 6. 启动后台轮询任务，等待处理完成
+    pollDocumentStatus(userId, kbId, document.id, difyResult.document.id).catch(error => {
+      console.error('Failed to poll document status:', error);
+    });
+
+    // 7. 更新知识库统计
+    await updateKnowledgeBaseStats(kbId);
+
+    // 8. 转换BigInt为Number
+    return {
+      ...updatedDocument,
+      fileSizeBytes: Number(updatedDocument.fileSizeBytes),
+    };
+  } catch (error) {
+    // 上传失败，更新状态为error
+    await prisma.document.update({
+      where: { id: document.id },
+      data: {
+        status: 'error',
+        errorMessage: error instanceof Error ? error.message : 'Upload failed',
+      },
+    });
+
+    throw error;
+  }
+}
+
+/**
+ * 轮询文档处理状态
+ */
+async function pollDocumentStatus(
+  userId: string,
+  kbId: string,
+  documentId: string,
+  difyDocumentId: string,
+  maxAttempts: number = 30
+) {
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: { id: kbId, userId },
+  });
+
+  if (!knowledgeBase) {
+    return;
+  }
+
+  for (let i = 0; i < maxAttempts; i++) {
+    await new Promise(resolve => setTimeout(resolve, 2000)); // 等待2秒
+
+    try {
+      // 查询Dify中的文档状态
+      const difyDocument = await difyClient.getDocument(
+        knowledgeBase.difyDatasetId,
+        difyDocumentId
+      );
+
+      // 更新数据库中的状态
+      await prisma.document.update({
+        where: { id: documentId },
+        data: {
+          status: difyDocument.indexing_status,
+          progress: difyDocument.indexing_status === 'completed' ? 100 : 50 + (i * 2),
+          segmentsCount: difyDocument.indexing_status === 'completed' ? difyDocument.word_count : null,
+          tokensCount: difyDocument.indexing_status === 'completed' ? difyDocument.tokens : null,
+          processedAt: difyDocument.indexing_status === 'completed' ? new Date() : null,
+          errorMessage: difyDocument.error || null,
+        },
+      });
+
+      // 如果完成或失败，退出轮询
+      if (difyDocument.indexing_status === 'completed') {
+        await updateKnowledgeBaseStats(kbId);
+        break;
+      }
+
+      if (difyDocument.indexing_status === 'error') {
+        break;
+      }
+    } catch (error) {
+      console.error(`Polling attempt ${i + 1} failed:`, error);
+    }
+  }
+}
+
+/**
+ * 获取文档列表
+ */
+export async function getDocuments(userId: string, kbId: string) {
+  // 1. 验证权限
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 查询文档列表
+  const documents = await prisma.document.findMany({
+    where: { kbId },
+    orderBy: { uploadedAt: 'desc' },
+  });
+
+  // 3. 转换BigInt为Number
+  return documents.map(doc => ({
+    ...doc,
+    fileSizeBytes: Number(doc.fileSizeBytes),
+  }));
+}
+
+/**
+ * 获取文档详情
+ */
+export async function getDocumentById(userId: string, documentId: string) {
+  const document = await prisma.document.findFirst({
+    where: {
+      id: documentId,
+      userId,  // 确保只能访问自己的文档
+    },
+    include: {
+      knowledgeBase: true,
+    },
+  });
+
+  if (!document) {
+    throw new Error('Document not found or access denied');
+  }
+
+  // 转换BigInt为Number
+  return {
+    ...document,
+    fileSizeBytes: Number(document.fileSizeBytes),
+    knowledgeBase: {
+      ...document.knowledgeBase,
+      totalSizeBytes: Number(document.knowledgeBase.totalSizeBytes),
+    },
+  };
+}
+
+/**
+ * 删除文档
+ */
+export async function deleteDocument(userId: string, documentId: string) {
+  // 1. 查询文档信息
+  const document = await prisma.document.findFirst({
+    where: {
+      id: documentId,
+      userId,
+    },
+    include: {
+      knowledgeBase: true,
+    },
+  });
+
+  if (!document) {
+    throw new Error('Document not found or access denied');
+  }
+
+  // 2. 删除Dify中的文档
+  if (document.difyDocumentId) {
+    try {
+      await difyClient.deleteDocument(
+        document.knowledgeBase.difyDatasetId,
+        document.difyDocumentId
+      );
+    } catch (error) {
+      console.error('Failed to delete Dify document:', error);
+      // 继续删除本地记录
+    }
+  }
+
+  // 3. 删除数据库记录
+  await prisma.document.delete({
+    where: { id: documentId },
+  });
+
+  // 4. 更新知识库统计
+  await updateKnowledgeBaseStats(document.kbId);
+}
+
+/**
+ * 重新处理文档
+ */
+export async function reprocessDocument(userId: string, documentId: string) {
+  // 1. 查询文档信息
+  const document = await prisma.document.findFirst({
+    where: {
+      id: documentId,
+      userId,
+    },
+    include: {
+      knowledgeBase: true,
+    },
+  });
+
+  if (!document) {
+    throw new Error('Document not found or access denied');
+  }
+
+  // 2. 触发Dify重新索引
+  if (document.difyDocumentId) {
+    try {
+      await difyClient.updateDocument(
+        document.knowledgeBase.difyDatasetId,
+        document.difyDocumentId
+      );
+
+      // 3. 更新状态为processing
+      await prisma.document.update({
+        where: { id: documentId },
+        data: {
+          status: 'parsing',
+          progress: 0,
+          errorMessage: null,
+        },
+      });
+
+      // 4. 启动轮询
+      pollDocumentStatus(
+        userId,
+        document.kbId,
+        documentId,
+        document.difyDocumentId
+      ).catch(error => {
+        console.error('Failed to poll document status:', error);
+      });
+    } catch (error) {
+      throw new Error('Failed to reprocess document');
+    }
+  }
+}
+
+/**
+ * 更新知识库统计信息
+ */
+async function updateKnowledgeBaseStats(kbId: string) {
+  const documents = await prisma.document.findMany({
+    where: { kbId },
+  });
+
+  const totalSizeBytes = documents.reduce((sum, d) => sum + Number(d.fileSizeBytes), 0);
+  const fileCount = documents.length;
+
+  await prisma.knowledgeBase.update({
+    where: { id: kbId },
+    data: {
+      fileCount,
+      totalSizeBytes: BigInt(totalSizeBytes),
+    },
+  });
+}
+
diff --git a/backend/src/services/knowledgeBaseService.ts b/backend/src/services/knowledgeBaseService.ts
new file mode 100644
index 00000000..eae7cc10
--- /dev/null
+++ b/backend/src/services/knowledgeBaseService.ts
@@ -0,0 +1,261 @@
+import { prisma } from '../config/database.js';
+import { difyClient } from '../clients/DifyClient.js';
+
+/**
+ * 知识库服务
+ */
+
+/**
+ * 创建知识库
+ */
+export async function createKnowledgeBase(
+  userId: string,
+  name: string,
+  description?: string
+) {
+  // 1. 检查用户知识库配额
+  const user = await prisma.user.findUnique({
+    where: { id: userId },
+    select: { kbQuota: true, kbUsed: true }
+  });
+
+  if (!user) {
+    throw new Error('User not found');
+  }
+
+  if (user.kbUsed >= user.kbQuota) {
+    throw new Error(`Knowledge base quota exceeded. Maximum: ${user.kbQuota}`);
+  }
+
+  // 2. 在Dify中创建Dataset
+  const difyDataset = await difyClient.createDataset({
+    name: `${userId}_${name}_${Date.now()}`,
+    description: description || `Knowledge base for user ${userId}`,
+    indexing_technique: 'high_quality',
+  });
+
+  // 3. 在数据库中创建记录
+  const knowledgeBase = await prisma.knowledgeBase.create({
+    data: {
+      userId,
+      name,
+      description,
+      difyDatasetId: difyDataset.id,
+    },
+  });
+
+  // 4. 更新用户的知识库使用计数
+  await prisma.user.update({
+    where: { id: userId },
+    data: {
+      kbUsed: { increment: 1 },
+    },
+  });
+
+  // 5. 转换BigInt为Number
+  return {
+    ...knowledgeBase,
+    totalSizeBytes: Number(knowledgeBase.totalSizeBytes),
+  };
+}
+
+/**
+ * 获取用户的知识库列表
+ */
+export async function getKnowledgeBases(userId: string) {
+  const knowledgeBases = await prisma.knowledgeBase.findMany({
+    where: { userId },
+    orderBy: { createdAt: 'desc' },
+    include: {
+      _count: {
+        select: { documents: true },
+      },
+    },
+  });
+
+  // 转换BigInt为Number
+  return knowledgeBases.map(kb => ({
+    ...kb,
+    totalSizeBytes: Number(kb.totalSizeBytes),
+  }));
+}
+
+/**
+ * 获取知识库详情
+ */
+export async function getKnowledgeBaseById(userId: string, kbId: string) {
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,  // 确保只能访问自己的知识库
+    },
+    include: {
+      documents: {
+        orderBy: { uploadedAt: 'desc' },
+      },
+      _count: {
+        select: { documents: true },
+      },
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 转换BigInt为Number
+  const result = {
+    ...knowledgeBase,
+    totalSizeBytes: Number(knowledgeBase.totalSizeBytes),
+    documents: knowledgeBase.documents.map(doc => ({
+      ...doc,
+      fileSizeBytes: Number(doc.fileSizeBytes),
+    })),
+  };
+
+  return result;
+}
+
+/**
+ * 更新知识库
+ */
+export async function updateKnowledgeBase(
+  userId: string,
+  kbId: string,
+  data: { name?: string; description?: string }
+) {
+  // 1. 验证权限
+  const existingKb = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+  });
+
+  if (!existingKb) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 更新数据库
+  const knowledgeBase = await prisma.knowledgeBase.update({
+    where: { id: kbId },
+    data,
+  });
+
+  // 3. 转换BigInt为Number
+  return {
+    ...knowledgeBase,
+    totalSizeBytes: Number(knowledgeBase.totalSizeBytes),
+  };
+}
+
+/**
+ * 删除知识库
+ */
+export async function deleteKnowledgeBase(userId: string, kbId: string) {
+  // 1. 验证权限
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 删除Dify中的Dataset
+  try {
+    await difyClient.deleteDataset(knowledgeBase.difyDatasetId);
+  } catch (error) {
+    console.error('Failed to delete Dify dataset:', error);
+    // 继续删除本地记录，即使Dify删除失败
+  }
+
+  // 3. 删除数据库记录（会级联删除documents）
+  await prisma.knowledgeBase.delete({
+    where: { id: kbId },
+  });
+
+  // 4. 更新用户的知识库使用计数
+  await prisma.user.update({
+    where: { id: userId },
+    data: {
+      kbUsed: { decrement: 1 },
+    },
+  });
+}
+
+/**
+ * 检索知识库
+ */
+export async function searchKnowledgeBase(
+  userId: string,
+  kbId: string,
+  query: string,
+  topK: number = 3
+) {
+  // 1. 验证权限
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 调用Dify检索API
+  const results = await difyClient.retrieveKnowledge(
+    knowledgeBase.difyDatasetId,
+    query,
+    {
+      retrieval_model: {
+        search_method: 'semantic_search',
+        top_k: topK,
+        score_threshold_enabled: true,
+        score_threshold: 0.3,
+      },
+    }
+  );
+
+  return results;
+}
+
+/**
+ * 获取知识库统计信息
+ */
+export async function getKnowledgeBaseStats(userId: string, kbId: string) {
+  // 1. 验证权限
+  const knowledgeBase = await prisma.knowledgeBase.findFirst({
+    where: {
+      id: kbId,
+      userId,
+    },
+    include: {
+      documents: true,
+    },
+  });
+
+  if (!knowledgeBase) {
+    throw new Error('Knowledge base not found or access denied');
+  }
+
+  // 2. 统计信息
+  const stats = {
+    totalDocuments: knowledgeBase.documents.length,
+    completedDocuments: knowledgeBase.documents.filter(d => d.status === 'completed').length,
+    processingDocuments: knowledgeBase.documents.filter(d => 
+      ['uploading', 'parsing', 'indexing'].includes(d.status)
+    ).length,
+    errorDocuments: knowledgeBase.documents.filter(d => d.status === 'error').length,
+    totalSizeBytes: knowledgeBase.totalSizeBytes,
+    totalTokens: knowledgeBase.documents.reduce((sum, d) => sum + (d.tokensCount || 0), 0),
+  };
+
+  return stats;
+}
+
diff --git a/backend/test-kb-api.ps1 b/backend/test-kb-api.ps1
new file mode 100644
index 00000000..889be566
--- /dev/null
+++ b/backend/test-kb-api.ps1
@@ -0,0 +1,111 @@
+# 测试知识库API脚本
+
+Write-Host "========================================" -ForegroundColor Cyan
+Write-Host "  测试知识库API" -ForegroundColor Cyan
+Write-Host "========================================" -ForegroundColor Cyan
+Write-Host ""
+
+# 测试1: 创建知识库
+Write-Host "测试1: 创建知识库..." -ForegroundColor Yellow
+$createBody = @{
+    name = "Test Knowledge Base"
+    description = "This is a test knowledge base"
+} | ConvertTo-Json
+
+try {
+    $result1 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases" `
+        -Method Post `
+        -Body $createBody `
+        -ContentType "application/json"
+    
+    Write-Host "✓ 创建成功" -ForegroundColor Green
+    Write-Host "  知识库ID: $($result1.data.id)" -ForegroundColor Gray
+    Write-Host "  名称: $($result1.data.name)" -ForegroundColor Gray
+    $kbId = $result1.data.id
+} catch {
+    Write-Host "✗ 创建失败: $_" -ForegroundColor Red
+    exit 1
+}
+
+Write-Host ""
+
+# 测试2: 获取知识库列表
+Write-Host "测试2: 获取知识库列表..." -ForegroundColor Yellow
+try {
+    $result2 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases" `
+        -Method Get
+    
+    Write-Host "✓ 获取成功" -ForegroundColor Green
+    Write-Host "  知识库数量: $($result2.data.Count)" -ForegroundColor Gray
+} catch {
+    Write-Host "✗ 获取失败: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# 测试3: 获取知识库详情
+Write-Host "测试3: 获取知识库详情..." -ForegroundColor Yellow
+try {
+    $result3 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases/$kbId" `
+        -Method Get
+    
+    Write-Host "✓ 获取成功" -ForegroundColor Green
+    Write-Host "  名称: $($result3.data.name)" -ForegroundColor Gray
+    Write-Host "  文档数: $($result3.data._count.documents)" -ForegroundColor Gray
+} catch {
+    Write-Host "✗ 获取失败: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# 测试4: 更新知识库
+Write-Host "测试4: 更新知识库..." -ForegroundColor Yellow
+$updateBody = @{
+    name = "Updated Test KB"
+    description = "Updated description"
+} | ConvertTo-Json
+
+try {
+    $result4 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases/$kbId" `
+        -Method Put `
+        -Body $updateBody `
+        -ContentType "application/json"
+    
+    Write-Host "✓ 更新成功" -ForegroundColor Green
+    Write-Host "  新名称: $($result4.data.name)" -ForegroundColor Gray
+} catch {
+    Write-Host "✗ 更新失败: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# 测试5: 检索知识库
+Write-Host "测试5: 检索知识库..." -ForegroundColor Yellow
+try {
+    $result5 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases/$kbId/search?query=test" `
+        -Method Get
+    
+    Write-Host "✓ 检索成功" -ForegroundColor Green
+    Write-Host "  结果数: $($result5.data.records.Count)" -ForegroundColor Gray
+} catch {
+    Write-Host "✗ 检索失败: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+
+# 测试6: 删除知识库
+Write-Host "测试6: 删除知识库..." -ForegroundColor Yellow
+try {
+    $result6 = Invoke-RestMethod -Uri "http://localhost:3001/api/v1/knowledge-bases/$kbId" `
+        -Method Delete
+    
+    Write-Host "✓ 删除成功" -ForegroundColor Green
+} catch {
+    Write-Host "✗ 删除失败: $_" -ForegroundColor Red
+}
+
+Write-Host ""
+Write-Host "========================================" -ForegroundColor Cyan
+Write-Host "  测试完成!" -ForegroundColor Cyan
+Write-Host "========================================" -ForegroundColor Cyan
+