diff --git a/back/main.py b/back/main.py
index 35e16af..f86dbfd 100644
--- a/back/main.py
+++ b/back/main.py
@@ -97,6 +97,15 @@ class ImgFile(db.Model):
     name = db.Column(db.String(255), nullable=True)
     identity_token = db.Column(db.String(36), nullable=True)
 
+class SiteNotice(db.Model):
+    __tablename__ = 'site_notice'
+    id = db.Column(db.Integer, primary_key=True, autoincrement=True)
+    type = db.Column(db.String(10), default='md', nullable=False)
+    content = db.Column(db.Text, default='', nullable=False)
+    version = db.Column(db.Integer, default=0, nullable=False)
+    created_at = db.Column(db.DateTime, default=lambda: datetime.now())
+    updated_at = db.Column(db.DateTime, default=lambda: datetime.now(), onupdate=datetime.now)
+
 # 初始化数据库函数
 def init_db():
     if not os.path.exists('./data'):
@@ -105,6 +114,14 @@ def init_db():
         os.makedirs(IMG_DIR)
     with app.app_context():
         db.create_all()
+        try:
+            existing = SiteNotice.query.first()
+            if not existing:
+                n = SiteNotice(type='md', content='', version=0)
+                db.session.add(n)
+                db.session.commit()
+        except Exception:
+            db.session.rollback()
 
 def load_config():
     global NEED_AUDIT, FILE_SIZE_LIMIT_MB, FILE_FORMATS
@@ -180,6 +197,23 @@ def get_about():
             "data": "# 默认关于页面\n关于页面未设置，请前往管理面板操作。"
         })
 
+@app.route('/api/site_notice', methods=['GET'])
+def get_site_notice():
+    try:
+        notice = SiteNotice.query.order_by(SiteNotice.id.asc()).first()
+        if not notice:
+            notice = SiteNotice(type='md', content='', version=0)
+            db.session.add(notice)
+            db.session.commit()
+        data = {
+            "type": notice.type if notice.type in ['md', 'url'] else 'md',
+            "content": notice.content or '',
+            "version": int(notice.version or 0),
+        }
+        return jsonify({"code": 1000, "data": data})
+    except Exception as e:
+        return jsonify({"code": 2003, "data": str(e)})
+
 @app.route('/api/get_id_token', methods=['GET'])
 def get_id_token():
     try:
diff --git a/front/src/App.tsx b/front/src/App.tsx
index 7a22fb3..9d4ff19 100644
--- a/front/src/App.tsx
+++ b/front/src/App.tsx
@@ -6,10 +6,12 @@ import About from './components/About';
 import CreatePost from './components/CreatePost';
 import PostCard from './components/PostCard';
 import ImageViewer from './components/ImageViewer';
-import { fetchArticles, reset_identity_token, type Article } from './api';
+import { fetchArticles, reset_identity_token, getSiteNotice, type Article } from './api';
 import { useLayout } from './context/LayoutContext';
 import './App.css';
 import { Eye24Regular, EyeOff24Regular, Copy24Regular } from '@fluentui/react-icons';
+import NoticeModal from './components/NoticeModal';
+import type { NoticeData } from './components/NoticeModal';
 
 const Home: React.FC<{ onPreviewImage: (src: string, alt?: string) => void }> = ({ onPreviewImage }) => {
   const { refreshTrigger } = useLayout();
@@ -152,6 +154,55 @@ const Home: React.FC<{ onPreviewImage: (src: string, alt?: string) => void }> =
 
 const NotFound = () => <h1>404 Not Found</h1>;
 
+const NoticeOverlay: React.FC = () => {
+  const { settings } = useLayout();
+  const [noticeData, setNoticeData] = useState<NoticeData | null>(null);
+  const [showNotice, setShowNotice] = useState(false);
+
+  useEffect(() => {
+    if (!settings || settings.enableNotice !== true) {
+      setShowNotice(false);
+      return;
+    }
+    getSiteNotice().then(data => {
+      const savedVersion = localStorage.getItem('site_notice_version');
+      if (data.content && (!savedVersion || Number(savedVersion) < Number(data.version))) {
+        setNoticeData({
+          type: data.type,
+          content: data.content,
+          version: data.version,
+        });
+        setShowNotice(true);
+      }
+    }).catch(console.error);
+  }, [settings]);
+
+  if (!showNotice || !noticeData) return null;
+  return (
+    <div style={{
+      position: 'fixed',
+      top: 0,
+      left: 0,
+      right: 0,
+      bottom: 0,
+      backgroundColor: 'rgba(0, 0, 0, 0.5)',
+      zIndex: 2000,
+      display: 'flex',
+      alignItems: 'center',
+      justifyContent: 'center',
+    }}>
+      <NoticeModal
+        data={noticeData}
+        onClose={() => setShowNotice(false)}
+        onNeverShow={(version) => {
+          localStorage.setItem('site_notice_version', String(version));
+          setShowNotice(false);
+        }}
+      />
+    </div>
+  );
+};
+
 function App() {
   const [imageViewer, setImageViewer] = useState<{ open: boolean; src?: string; alt?: string }>({ open: false });
   const openImageViewer = (src?: string, alt?: string) => {
@@ -254,6 +305,7 @@ function App() {
                       </DialogBody>
                     </DialogSurface>
                   </Dialog>
+                  <NoticeOverlay />
                 </>
               }
             />
diff --git a/front/src/api.ts b/front/src/api.ts
index 2b37abb..c260f38 100644
--- a/front/src/api.ts
+++ b/front/src/api.ts
@@ -4,6 +4,7 @@ export interface SiteSettings {
   enableCodeIcon: boolean;
   repoUrl: string;
   favicon: string;
+  enableNotice?: boolean;
   fileSizeLimit?: number;
   fileFormats?: string[];
 }
@@ -38,6 +39,7 @@ export const getSettings = async (): Promise<SiteSettings> => {
         enableCodeIcon: data.enable_repo_button ?? true,
         repoUrl: data.repo_link,
         favicon: data.icon,
+        enableNotice: data.enable_notice ?? false,
         fileSizeLimit: data.file_size_limit != null ? Number(data.file_size_limit) : undefined,
         fileFormats,
       };
@@ -74,6 +76,12 @@ export interface StaticsData {
   images: number;
 }
 
+export interface SiteNoticeData {
+  type: 'md' | 'url';
+  content: string;
+  version: number;
+}
+
 export interface HotTopicItem {
   name: string;
   count: number;
@@ -141,6 +149,27 @@ export const get_id_token = async (): Promise<string> => {
   return token;
 };
 
+export const getSiteNotice = async (): Promise<SiteNoticeData> => {
+  try {
+    const response = await fetch('/api/site_notice');
+    if (!response.ok) {
+      throw new Error(`HTTP error! status: ${response.status}`);
+    }
+    const json = await response.json();
+    if (json.code === 1000 && json.data) {
+      return {
+        type: (json.data.type === 'url' ? 'url' : 'md') as 'md' | 'url',
+        content: String(json.data.content ?? ''),
+        version: Number(json.data.version ?? 0),
+      };
+    }
+    throw new Error('Invalid response code or missing data');
+  } catch (error) {
+    console.error('Failed to fetch site notice:', error);
+    throw error;
+  }
+};
+
 const notifyInvalidIdentity = () => {
   if (typeof window !== 'undefined') {
     window.dispatchEvent(new CustomEvent('identity_invalid'));
diff --git a/front/src/components/NoticeModal.tsx b/front/src/components/NoticeModal.tsx
new file mode 100644
index 0000000..64b7db1
--- /dev/null
+++ b/front/src/components/NoticeModal.tsx
@@ -0,0 +1,93 @@
+import React from 'react';
+import { makeStyles, Button, tokens, Text } from '@fluentui/react-components';
+import { Dismiss24Regular } from '@fluentui/react-icons';
+import ReactMarkdown from 'react-markdown';
+import remarkGfm from 'remark-gfm';
+import remarkIns from 'remark-ins';
+import remarkBreaks from 'remark-breaks';
+
+const useStyles = makeStyles({
+  modalContent: {
+    backgroundColor: tokens.colorNeutralBackground1,
+    padding: tokens.spacingHorizontalXXL,
+    borderRadius: tokens.borderRadiusXLarge,
+    boxShadow: tokens.shadow64,
+    display: 'flex',
+    flexDirection: 'column',
+    gap: tokens.spacingVerticalM,
+    width: '520px',
+    maxWidth: '90vw',
+    position: 'relative',
+  },
+  closeButton: {
+    position: 'absolute',
+    top: tokens.spacingVerticalS,
+    right: tokens.spacingHorizontalS,
+  },
+  title: {
+    fontSize: tokens.fontSizeBase500,
+    fontWeight: tokens.fontWeightSemibold,
+    marginBottom: tokens.spacingVerticalS,
+  },
+  contentBox: {
+    maxHeight: '60vh',
+    overflowY: 'auto',
+  },
+  iframe: {
+    width: '100%',
+    height: '360px',
+    border: 'none',
+    borderRadius: tokens.borderRadiusMedium,
+    backgroundColor: tokens.colorNeutralBackground2,
+  },
+  actions: {
+    display: 'flex',
+    justifyContent: 'flex-end',
+    gap: tokens.spacingHorizontalS,
+  },
+});
+
+export interface NoticeData {
+  type: 'md' | 'url';
+  content: string;
+  version: number;
+}
+
+interface NoticeModalProps {
+  data: NoticeData;
+  onClose: () => void;
+  onNeverShow: (version: number) => void;
+}
+
+const NoticeModal: React.FC<NoticeModalProps> = ({ data, onClose, onNeverShow }) => {
+  const styles = useStyles();
+  const { type, content, version } = data;
+
+  return (
+    <div className={styles.modalContent} role="dialog" aria-modal="true" aria-label="公告">
+      <Button
+        icon={<Dismiss24Regular />}
+        appearance="transparent"
+        className={styles.closeButton}
+        onClick={onClose}
+        aria-label="关闭"
+      />
+      <Text as="h2" className={styles.title}>公告</Text>
+      <div className={styles.contentBox}>
+        {type === 'md' ? (
+          <ReactMarkdown remarkPlugins={[remarkGfm, remarkIns, remarkBreaks]}>
+            {content}
+          </ReactMarkdown>
+        ) : (
+          <iframe className={styles.iframe} src={content} title={`公告-${version}`} />
+        )}
+      </div>
+      <div className={styles.actions}>
+        <Button appearance="primary" onClick={onClose}>确定</Button>
+        <Button appearance="subtle" onClick={() => onNeverShow(version)}>不再显示</Button>
+      </div>
+    </div>
+  );
+};
+
+export default NoticeModal;