diff --git a/backend/app.py b/backend/app.py
index 30b3913..412a05e 100644
--- a/backend/app.py
+++ b/backend/app.py
@@ -166,6 +166,20 @@ def init_db():
         )
     ''')
     
+    # 对话表（用户对话数据）
+    cursor.execute('''
+        CREATE TABLE IF NOT EXISTS conversations (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            user_id INTEGER NOT NULL,
+            title TEXT NOT NULL,
+            agent_id TEXT,
+            messages TEXT NOT NULL DEFAULT '[]',
+            created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+            FOREIGN KEY (user_id) REFERENCES users(id)
+        )
+    ''')
+    
     # 初始化默认大模型配置
     cursor.execute('SELECT COUNT(*) FROM llm_configs')
     if cursor.fetchone()[0] == 0:
@@ -581,6 +595,118 @@ def change_user_password(id):
     return jsonify({'success': True})
 
 
+# ==================== 用户对话数据同步 ====================
+
+@app.route('/api/user/<int:user_id>/conversations', methods=['GET'])
+def get_user_conversations(user_id):
+    """获取用户所有对话"""
+    conn = get_db()
+    cursor = conn.cursor()
+    cursor.execute('''
+        SELECT id, title, agent_id, messages, created_at, updated_at 
+        FROM conversations WHERE user_id = ? ORDER BY updated_at DESC
+    ''', (user_id,))
+    
+    conversations = []
+    for row in cursor.fetchall():
+        conv = dict(row)
+        # 解析消息JSON
+        try:
+            conv['messages'] = json.loads(conv['messages']) if conv['messages'] else []
+        except:
+            conv['messages'] = []
+        # 转换为前端格式（使用字符串ID）
+        conv['id'] = str(conv['id'])
+        conv['createdAt'] = int(datetime.strptime(conv['created_at'], '%Y-%m-%d %H:%M:%S').timestamp() * 1000) if conv['created_at'] else 0
+        conv['updatedAt'] = int(datetime.strptime(conv['updated_at'], '%Y-%m-%d %H:%M:%S').timestamp() * 1000) if conv['updated_at'] else 0
+        conv['agentId'] = conv['agent_id']
+        conversations.append(conv)
+    
+    conn.close()
+    return jsonify(conversations)
+
+
+@app.route('/api/user/<int:user_id>/conversations', methods=['POST'])
+def create_user_conversation(user_id):
+    """创建新对话"""
+    data = request.json
+    title = data.get('title', '新对话')
+    agent_id = data.get('agentId') or data.get('agent_id')
+    messages = data.get('messages', [])
+    
+    conn = get_db()
+    cursor = conn.cursor()
+    cursor.execute('''
+        INSERT INTO conversations (user_id, title, agent_id, messages)
+        VALUES (?, ?, ?, ?)
+    ''', (user_id, title, agent_id, json.dumps(messages)))
+    conn.commit()
+    
+    conv_id = cursor.lastrowid
+    conn.close()
+    
+    return jsonify({'success': True, 'id': str(conv_id)})
+
+
+@app.route('/api/user/<int:user_id>/conversations/<int:conv_id>', methods=['PUT'])
+def update_user_conversation(user_id, conv_id):
+    """更新对话（添加消息、修改标题等）"""
+    data = request.json
+    conn = get_db()
+    cursor = conn.cursor()
+    
+    # 验证对话属于该用户
+    cursor.execute('SELECT id FROM conversations WHERE id = ? AND user_id = ?', (conv_id, user_id))
+    if not cursor.fetchone():
+        conn.close()
+        return jsonify({'error': '对话不存在'}), 404
+    
+    # 更新字段
+    updates = []
+    values = []
+    
+    if 'title' in data:
+        updates.append('title = ?')
+        values.append(data['title'])
+    
+    if 'messages' in data:
+        updates.append('messages = ?')
+        values.append(json.dumps(data['messages']))
+    
+    if 'agentId' in data or 'agent_id' in data:
+        updates.append('agent_id = ?')
+        values.append(data.get('agentId') or data.get('agent_id'))
+    
+    if updates:
+        updates.append('updated_at = CURRENT_TIMESTAMP')
+        sql = f'UPDATE conversations SET {", ".join(updates)} WHERE id = ?'
+        values.append(conv_id)
+        cursor.execute(sql, values)
+        conn.commit()
+    
+    conn.close()
+    return jsonify({'success': True})
+
+
+@app.route('/api/user/<int:user_id>/conversations/<int:conv_id>', methods=['DELETE'])
+def delete_user_conversation(user_id, conv_id):
+    """删除对话"""
+    conn = get_db()
+    cursor = conn.cursor()
+    
+    # 验证对话属于该用户
+    cursor.execute('SELECT id FROM conversations WHERE id = ? AND user_id = ?', (conv_id, user_id))
+    if not cursor.fetchone():
+        conn.close()
+        return jsonify({'error': '对话不存在'}), 404
+    
+    cursor.execute('DELETE FROM conversations WHERE id = ?', (conv_id,))
+    conn.commit()
+    conn.close()
+    
+    return jsonify({'success': True})
+
+
 # ==================== 大模型接口管理 ====================
 
 @app.route('/api/admin/llm', methods=['GET'])
diff --git a/www/app.js b/www/app.js
index d304b99..8a19d92 100644
--- a/www/app.js
+++ b/www/app.js
@@ -1620,14 +1620,43 @@ function showEditProfilePage() {
     return;
   }
   
-  // 获取完整用户信息
-  const users = JSON.parse(localStorage.getItem('registeredUsers') || '[]');
-  const fullUser = users.find(u => u.username === currentUser.username);
-  
+  // 如果用户已登录且有ID，从 backend 获取完整用户信息
+  if (currentUser.id) {
+    fetch(`/api/admin/users/${currentUser.id}`)
+      .then(res => res.json())
+      .then(data => {
+        if (data && data.id) {
+          // 更新 currentUser 的完整信息
+          currentUser.avatar = data.avatar || '👤';
+          currentUser.signature = data.signature || '';
+          currentUser.email = data.email || '';
+          currentUser.gender = data.gender || '';
+          currentUser.age = data.age || '';
+          currentUser.region = data.region || '';
+          currentUser.phone = data.phone || '';
+          
+          // 渲染编辑页面
+          renderEditProfilePage();
+        } else {
+          // 使用本地数据
+          renderEditProfilePage();
+        }
+      })
+      .catch(e => {
+        // 使用本地数据
+        renderEditProfilePage();
+      });
+  } else {
+    // 游客用户，使用本地数据
+    renderEditProfilePage();
+  }
+}
+
+function renderEditProfilePage() {
   const avatar = currentUser.avatar || '👤';
   const signature = currentUser.signature || '';
-  const phone = fullUser?.phone || '';
-  const email = fullUser?.email || '';
+  const phone = currentUser.phone || '';
+  const email = currentUser.email || '';
   const gender = currentUser.gender || '';
   const age = currentUser.age || '';
   const region = currentUser.region || '';
@@ -1773,26 +1802,6 @@ function handleSaveProfile() {
     return;
   }
   
-  // 检查用户名是否被其他人占用
-  const users = JSON.parse(localStorage.getItem('registeredUsers') || '[]');
-  if (newUsername !== currentUser.username) {
-    if (users.find(u => u.username === newUsername)) {
-      showToast('用户名已被占用');
-      return;
-    }
-    // 更新用户名
-    const userIndex = users.findIndex(u => u.username === currentUser.username);
-    if (userIndex >= 0) {
-      users[userIndex].username = newUsername;
-    }
-  }
-  
-  // 更新邮箱
-  const userIndex = users.findIndex(u => u.username === currentUser.username);
-  if (userIndex >= 0) {
-    users[userIndex].email = newEmail;
-  }
-  
   // 更新 currentUser
   currentUser.avatar = newAvatar;
   currentUser.username = newUsername;
@@ -1800,12 +1809,42 @@ function handleSaveProfile() {
   currentUser.gender = newGender;
   currentUser.age = newAge ? parseInt(newAge) : '';
   currentUser.region = newRegion;
+  currentUser.email = newEmail;
   
-  saveCurrentUser();
-  localStorage.setItem('registeredUsers', JSON.stringify(users));
-  
-  showToast('保存成功');
-  switchPage('profile');
+  // 如果用户已登录，调用 backend API 更新
+  if (currentUser.id) {
+    fetch(`/api/user/${currentUser.id}`, {
+      method: 'PUT',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        username: newUsername,
+        email: newEmail,
+        avatar: newAvatar,
+        signature: newSignature,
+        gender: newGender,
+        age: newAge ? parseInt(newAge) : null,
+        region: newRegion
+      })
+    })
+    .then(res => res.json())
+    .then(data => {
+      if (data.success) {
+        saveCurrentUser();
+        showToast('保存成功');
+        switchPage('profile');
+      } else {
+        showToast(data.error || '保存失败');
+      }
+    })
+    .catch(e => {
+      showToast('网络错误，请重试');
+    });
+  } else {
+    // 未登录用户，保存到本地
+    saveCurrentUser();
+    showToast('保存成功');
+    switchPage('profile');
+  }
 }
 
 // ==================== 消息通知页面 ====================
@@ -2466,8 +2505,12 @@ function handleLogin() {
         registeredAt: Date.now()
       };
       saveCurrentUser();
-      showToast('登录成功');
-      showMainPage();
+      
+      // 从 backend 加载用户对话数据
+      loadUserConversations().then(() => {
+        showToast('登录成功');
+        showMainPage();
+      });
     } else {
       showToast(data.error || '用户名或密码错误');
     }
@@ -2633,8 +2676,12 @@ function handleRegister() {
         registeredAt: Date.now()
       };
       saveCurrentUser();
-      showToast('注册成功');
-      showMainPage();
+      
+      // 加载对话数据（新用户为空）
+      loadUserConversations().then(() => {
+        showToast('注册成功');
+        showMainPage();
+      });
     } else {
       showToast(data.error || '注册失败');
     }
@@ -3496,6 +3543,17 @@ function deleteConversation(id) {
   
   conversations = conversations.filter(c => c.id !== id);
   saveConversations();
+  
+  // 如果用户已登录，从 backend 删除
+  if (currentUser && currentUser.id) {
+    const convId = parseInt(id);
+    if (convId > 0) {
+      fetch(`/api/user/${currentUser.id}/conversations/${convId}`, {
+        method: 'DELETE'
+      }).catch(e => console.error('删除对话失败:', e));
+    }
+  }
+  
   showConversationList();
 }
 
@@ -4166,7 +4224,91 @@ function setupScrollListener() {
 
 // 保存对话列表
 function saveConversations() {
+  // 保存到本地存储（离线可用）
   localStorage.setItem('conversations', JSON.stringify(conversations));
+  
+  // 如果用户已登录，同步到 backend
+  if (currentUser && currentUser.id) {
+    syncConversationsToBackend();
+  }
+}
+
+// 同步对话数据到 backend
+async function syncConversationsToBackend() {
+  if (!currentUser || !currentUser.id) return;
+  
+  try {
+    // 批量同步所有对话
+    for (const conv of conversations) {
+      const convId = parseInt(conv.id);
+      if (convId > 0) {
+        // 更新现有对话
+        await fetch(`/api/user/${currentUser.id}/conversations/${convId}`, {
+          method: 'PUT',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({
+            title: conv.title,
+            messages: conv.messages,
+            agentId: conv.agentId
+          })
+        });
+      } else {
+        // 新对话，需要创建
+        const res = await fetch(`/api/user/${currentUser.id}/conversations`, {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({
+            title: conv.title,
+            messages: conv.messages,
+            agentId: conv.agentId
+          })
+        });
+        const data = await res.json();
+        if (data.success && data.id) {
+          // 更新本地ID为backend ID
+          conv.id = data.id;
+        }
+      }
+    }
+  } catch (e) {
+    // 同步失败，静默处理（下次登录时会重新加载）
+    console.error('同步对话失败:', e);
+  }
+}
+
+// 从 backend 加载用户对话数据
+async function loadUserConversations() {
+  if (!currentUser || !currentUser.id) return;
+  
+  try {
+    const res = await fetch(`/api/user/${currentUser.id}/conversations`);
+    const data = await res.json();
+    
+    if (Array.isArray(data)) {
+      // 合并本地和云端数据（云端优先）
+      const localConvIds = conversations.map(c => c.id);
+      
+      for (const cloudConv of data) {
+        const localIdx = localConvIds.indexOf(cloudConv.id);
+        if (localIdx >= 0) {
+          // 更新本地对话（云端数据优先）
+          conversations[localIdx] = cloudConv;
+        } else {
+          // 添加云端对话
+          conversations.push(cloudConv);
+        }
+      }
+      
+      // 按更新时间排序
+      conversations.sort((a, b) => b.updatedAt - a.updatedAt);
+      
+      // 保存到本地
+      localStorage.setItem('conversations', JSON.stringify(conversations));
+    }
+  } catch (e) {
+    console.error('加载对话失败:', e);
+    // 使用本地数据
+  }
 }
 
 // 显示提示