diff --git a/backend/cmd/main.go b/backend/cmd/main.go
index f7b89d9..16aab80 100644
--- a/backend/cmd/main.go
+++ b/backend/cmd/main.go
@@ -164,6 +164,18 @@ func main() {
 	// 注册路由
 	routes.Register(r, db, log, cfg, cache)
 
+	// 定期清理旧的 agent 上报数据（保留 7 天，防止表膨胀影响查询性能）
+	go func() {
+		ticker := time.NewTicker(24 * time.Hour)
+		defer ticker.Stop()
+		for range ticker.C {
+			result := db.Exec("DELETE FROM monitor_agent_reports WHERE report_time < DATE_SUB(NOW(), INTERVAL 7 DAY)")
+			if result.RowsAffected > 0 {
+				log.Info("清理过期的 agent 上报数据", zap.Int64("rows", result.RowsAffected))
+			}
+		}
+	}()
+
 	// 前端静态文件服务（go:embed 模式，二进制部署用） // Logan.Li
 	setupFrontend(r)
 
diff --git a/frontend/src/components/dashboard/Dashboard.tsx b/frontend/src/components/dashboard/Dashboard.tsx
index 9d1e114..b22bf19 100644
--- a/frontend/src/components/dashboard/Dashboard.tsx
+++ b/frontend/src/components/dashboard/Dashboard.tsx
@@ -62,7 +62,7 @@ export function Dashboard() {
           console.error('Failed to fetch dashboard releases:', e);
           return null;
         }),
-        dashboardStatsApi.getMetrics(24).catch((e) => {
+        dashboardStatsApi.getMetrics(6).catch((e) => {
           console.error('Failed to fetch metrics:', e);
           return [];
         }),
@@ -85,6 +85,9 @@ export function Dashboard() {
 
   useEffect(() => {
     refreshData();
+    // 每 5 分钟自动刷新
+    const interval = setInterval(refreshData, 5 * 60 * 1000);
+    return () => clearInterval(interval);
   }, [refreshData]);
 
   if (initialLoading) {