diff --git a/client/src/pages/admin/Export.tsx b/client/src/pages/admin/Export.tsx
index c12b96c..e5190a2 100644
--- a/client/src/pages/admin/Export.tsx
+++ b/client/src/pages/admin/Export.tsx
@@ -262,11 +262,19 @@ export default function Export() {
 
   const overviewCalc = (() => {
     if (!preview) return null;
-    const totalHours = (preview.hours || []).reduce((s: number, h: any) => s + Number(h.hours || 0), 0);
     const userCount = (preview.users || []).length;
     const activityCount = (preview.activities || []).length;
     const hourCount = (preview.hours || []).length;
-    const avgHours = userCount > 0 ? totalHours / userCount : 0;
+    let totalHours: number;
+    if (preview.user_totals && preview.user_totals.length > 0) {
+      totalHours = (preview.user_totals).reduce((s: number, u: any) => s + Number(u.total_hours || 0), 0);
+    } else if (preview.activity_matrix && Array.isArray(preview.activity_matrix.users)) {
+      totalHours = (preview.activity_matrix.users).reduce((s: number, u: any) => s + Number(u._total || 0), 0);
+    } else {
+      totalHours = (preview.hours || []).reduce((s: number, h: any) => s + Number(h.hours || 0), 0);
+    }
+    totalHours = Number(totalHours.toFixed(1));
+    const avgHours = userCount > 0 ? Number((totalHours / userCount).toFixed(1)) : 0;
     return { totalHours, userCount, activityCount, hourCount, avgHours };
   })();
 
diff --git a/client/src/pages/user/Dashboard.tsx b/client/src/pages/user/Dashboard.tsx
index 8707fb5..576dc3a 100644
--- a/client/src/pages/user/Dashboard.tsx
+++ b/client/src/pages/user/Dashboard.tsx
@@ -68,7 +68,19 @@ export default function UserDashboard() {
           <div className="mt-5 pt-5 border-t border-gray-200 grid grid-cols-2 gap-4">
             <div className="card p-4 bg-primary-50/50">
               <div className="muted mb-1">累计义工时长</div>
-              <div className="text-2xl md:text-3xl font-semibold text-primary-600">{Number(data.total_hours || 0).toFixed(1)} <span className="text-base font-medium text-gray-600">小时</span></div>
+              <div className="text-2xl md:text-3xl font-semibold text-primary-600">
+                {Number(data.total_hours || 0).toFixed(1)} <span className="text-base font-medium text-gray-600">小时</span>
+              </div>
+              {data.activities.length > 0 && (
+                <div className="mt-3 pt-3 border-t border-primary-200/60 flex items-center justify-between">
+                  <span className="text-[11px] text-gray-500">
+                    明细表合计：
+                  </span>
+                  <span className="text-sm font-bold text-primary-600">
+                    {data.activities.reduce((s, r) => s + Number((r as any).hours || 0), 0).toFixed(1)} 小时
+                  </span>
+                </div>
+              )}
             </div>
             <div className="card p-4">
               <div className="muted mb-1">参与活动数</div>
diff --git a/server/src/routes/export.ts b/server/src/routes/export.ts
index 6390391..258d914 100644
--- a/server/src/routes/export.ts
+++ b/server/src/routes/export.ts
@@ -66,11 +66,17 @@ router.post('/', authMiddleware, (req: AuthRequest, res) => {
                 FROM user_groups ug2
                 LEFT JOIN work_groups g2 ON ug2.group_id = g2.id
                 WHERE ug2.user_id = u.id) AS _group_names_csv,
-             COALESCE(SUM(h.hours), 0) AS total_hours,
-             COUNT(DISTINCT h.activity_id) AS activity_count
+             COALESCE(vh.total_hours, 0) AS total_hours,
+             COALESCE(vh.activity_count, 0) AS activity_count
       FROM users u
-      LEFT JOIN hours h ON h.user_id = u.id
-      GROUP BY u.id
+      LEFT JOIN (
+        SELECT user_id,
+               SUM(hours) AS total_hours,
+               COUNT(DISTINCT activity_id) AS activity_count
+          FROM hours h
+         WHERE EXISTS (SELECT 1 FROM activities a WHERE a.id = h.activity_id)
+         GROUP BY user_id
+      ) vh ON vh.user_id = u.id
       ORDER BY total_hours DESC, u.class, u.name
     `).all();
     result.user_totals = withGroupNames(rows).map(({ _group_names_csv: _, ...rest }) => rest);
@@ -112,7 +118,8 @@ router.post('/', authMiddleware, (req: AuthRequest, res) => {
     `).all() as any[];
     const users = withGroupNames(userRows);
     const hoursRows = db.prepareCompat(`
-      SELECT user_id, activity_id, hours, remark FROM hours
+      SELECT user_id, activity_id, hours, remark FROM hours h
+       WHERE EXISTS (SELECT 1 FROM activities a WHERE a.id = h.activity_id)
     `).all() as any[];
     const matrix: Record<string, number> = {};
     const remarkMatrix: Record<string, string> = {};
diff --git a/server/src/routes/users.ts b/server/src/routes/users.ts
index be319ca..9562a36 100644
--- a/server/src/routes/users.ts
+++ b/server/src/routes/users.ts
@@ -31,7 +31,11 @@ router.get('/', authMiddleware, (req: AuthRequest, res: Response) => {
     SELECT u.id, u.class, u.name, u.volunteer_no,
            GROUP_CONCAT(g.id) AS group_ids_csv,
            GROUP_CONCAT(g.name) AS group_names_csv,
-           COALESCE((SELECT SUM(h.hours) FROM hours h WHERE h.user_id = u.id), 0) AS total_hours
+           COALESCE((
+             SELECT SUM(h.hours) FROM hours h
+              WHERE h.user_id = u.id
+                AND EXISTS (SELECT 1 FROM activities a WHERE a.id = h.activity_id)
+           ), 0) AS total_hours
     FROM users u
     LEFT JOIN user_groups ug ON u.id = ug.user_id
     LEFT JOIN work_groups g ON ug.group_id = g.id
@@ -66,7 +70,11 @@ router.get('/:id', (req: Request, res: Response) => {
     SELECT u.id, u.class, u.name, u.volunteer_no,
            GROUP_CONCAT(g.id) AS group_ids_csv,
            GROUP_CONCAT(g.name) AS group_names_csv,
-           COALESCE((SELECT SUM(h.hours) FROM hours h WHERE h.user_id = u.id), 0) AS total_hours
+           COALESCE((
+             SELECT SUM(h.hours) FROM hours h
+              WHERE h.user_id = u.id
+                AND EXISTS (SELECT 1 FROM activities a WHERE a.id = h.activity_id)
+           ), 0) AS total_hours_raw
     FROM users u
     LEFT JOIN user_groups ug ON u.id = ug.user_id
     LEFT JOIN work_groups g ON ug.group_id = g.id