diff --git a/frontend/assets/styles.css b/frontend/assets/styles.css
index 7167f27..cd2862a 100644
--- a/frontend/assets/styles.css
+++ b/frontend/assets/styles.css
@@ -589,3 +589,30 @@ input[type="date"]::-webkit-calendar-picker-indicator:hover{
     font-size: 14px;
   }
 }
+
+/* Watermark styles */
+.watermark {
+  position: fixed;
+  top: 0;
+  left: 0;
+  width: 100%;
+  height: 100%;
+  pointer-events: none;
+  z-index: 9999;
+  overflow: hidden;
+}
+
+.watermark-text {
+  position: absolute;
+  font-size: 16px;
+  color: var(--text);
+  opacity: 0.08;
+  transform: rotate(-45deg);
+  white-space: nowrap;
+  user-select: none;
+  font-weight: 500;
+}
+
+[data-theme="light"] .watermark-text {
+  opacity: 0.06;
+}
diff --git a/frontend/js/app.js b/frontend/js/app.js
index a1aea0d..1e176bd 100644
--- a/frontend/js/app.js
+++ b/frontend/js/app.js
@@ -21,6 +21,58 @@
     } else if (avatarImg) {
       avatarImg.src = './assets/user-avatar.svg';
     }
+    
+    // 更新水印
+    if (user && user.username) {
+      createWatermark(user.username);
+    } else {
+      removeWatermark();
+    }
+  }
+  
+  // 创建水印
+  function createWatermark(username) {
+    // 检查水印是否启用
+    const watermarkEnabled = localStorage.getItem('watermarkEnabled');
+    if (watermarkEnabled === 'false') {
+      return;
+    }
+    
+    removeWatermark();
+    
+    const watermarkDiv = document.createElement('div');
+    watermarkDiv.id = 'watermark-container';
+    watermarkDiv.className = 'watermark';
+    
+    const now = new Date();
+    const dateStr = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, '0')}-${String(now.getDate()).padStart(2, '0')} ${String(now.getHours()).padStart(2, '0')}:${String(now.getMinutes()).padStart(2, '0')}`;
+    const watermarkText = `${username} ${dateStr}`;
+    
+    // 计算水印平铺
+    const spacing = 300;
+    const rows = Math.ceil(window.innerHeight / spacing) + 2;
+    const cols = Math.ceil(window.innerWidth / spacing) + 2;
+    
+    for (let i = 0; i < rows; i++) {
+      for (let j = 0; j < cols; j++) {
+        const span = document.createElement('span');
+        span.className = 'watermark-text';
+        span.textContent = watermarkText;
+        span.style.left = `${j * spacing - 100}px`;
+        span.style.top = `${i * spacing - 100}px`;
+        watermarkDiv.appendChild(span);
+      }
+    }
+    
+    document.body.appendChild(watermarkDiv);
+  }
+  
+  // 移除水印
+  function removeWatermark() {
+    const existing = document.getElementById('watermark-container');
+    if (existing) {
+      existing.remove();
+    }
   }
   
   Router.onBeforeEach(async (path) => {
@@ -84,6 +136,7 @@
     API.logout()
       .then(() => {
         currentUser = null;
+        removeWatermark();
         updateUserDisplay(null);
         userDropdown.style.display = 'none';
         location.hash = '#/login';
@@ -130,4 +183,14 @@
   
   // 暴露更新用户显示的函数，供设置页面使用
   window.updateUserDisplay = updateUserDisplay;
+  
+  // 暴露水印控制函数
+  window.toggleWatermark = function(enabled) {
+    localStorage.setItem('watermarkEnabled', enabled ? 'true' : 'false');
+    if (enabled && currentUser && currentUser.username) {
+      createWatermark(currentUser.username);
+    } else {
+      removeWatermark();
+    }
+  };
 })();
\ No newline at end of file
diff --git a/frontend/js/components/settings.js b/frontend/js/components/settings.js
index 3f2c338..6457261 100644
--- a/frontend/js/components/settings.js
+++ b/frontend/js/components/settings.js
@@ -64,6 +64,19 @@ Router.register('/settings', async () => {
         <div class="actions"><button id="change-btn" class="btn">修改密码</button></div>
       </div>
 
+      <div style="margin-bottom:24px;padding-bottom:24px;border-bottom:1px solid var(--border)">
+        <div style="font-weight:500;margin-bottom:12px">水印设置</div>
+        <div style="display:flex;align-items:center;gap:12px;padding:12px;background:var(--surface);border:1px solid var(--border);border-radius:8px">
+          <label style="flex:1;cursor:pointer;display:flex;align-items:center;gap:8px">
+            <input type="checkbox" id="watermark-toggle" ${localStorage.getItem('watermarkEnabled') !== 'false' ? 'checked' : ''} style="width:18px;height:18px;cursor:pointer" />
+            <span style="font-size:14px">启用页面水印（显示用户名和时间戳）</span>
+          </label>
+        </div>
+        <div style="margin-top:8px;font-size:12px;color:var(--text-2)">
+          水印用于防止数据泄露和责任追溯，建议保持启用状态
+        </div>
+      </div>
+
       <div style="font-weight:500;margin-bottom:12px">超级管理员工具</div>
       <div style="margin-top:12px"></div>
       <div class="grid cols-2" style="margin-top:8px">
@@ -288,6 +301,16 @@ Router.register('/settings', async () => {
         change.disabled = false;
       }
     });
+    
+    // 水印开关
+    const watermarkToggle = document.getElementById('watermark-toggle');
+    watermarkToggle?.addEventListener('change', (e) => {
+      const enabled = e.target.checked;
+      if (window.toggleWatermark) {
+        window.toggleWatermark(enabled);
+        API.toast(enabled ? '水印已启用' : '水印已关闭');
+      }
+    });
     document.querySelectorAll('button[data-clear]')?.forEach(btn => {
       btn.addEventListener('click', async () => {
         const mod = btn.getAttribute('data-clear');