diff --git a/cmd/safesightd/main.go b/cmd/safesightd/main.go
index b2baa5a..05fe142 100644
--- a/cmd/safesightd/main.go
+++ b/cmd/safesightd/main.go
@@ -6,6 +6,7 @@ import (
     "net/http"
     "os"
     "path/filepath"
+    "strconv"
 
 	"safesight-control/internal/api"
 	"safesight-control/internal/config"
@@ -75,9 +76,14 @@ func main() {
         log.Printf("load persisted tasks: %v", err)
     }
     alarmCollector := service.NewAlarmCollector(store.DB(), agentClient, regSvc)
-    if cfg.AlarmRetentionDays > 0 {
-        alarmCollector.SetRetention(cfg.AlarmRetentionDays)
+    // Load retention from DB (UI-persisted), fallback to config file
+    retention := cfg.AlarmRetentionDays
+    if persisted, err := storage.LoadSetting(store.DB(), "alarm_retention_days"); err == nil && persisted != "" {
+        if v, err := strconv.Atoi(persisted); err == nil && v >= 0 {
+            retention = v
+        }
     }
+    alarmCollector.SetRetention(retention)
     alarmCollector.Start()
     tplSvc := service.NewTemplateService(cfg)
     h := api.NewHandler(discoSvc, regSvc, agentClient, taskSvc, tplSvc)
diff --git a/internal/storage/migrate.go b/internal/storage/migrate.go
index 5b6ae87..19ffd3e 100644
--- a/internal/storage/migrate.go
+++ b/internal/storage/migrate.go
@@ -480,6 +480,10 @@ CREATE TABLE IF NOT EXISTS config_versions (
   config_id TEXT NOT NULL DEFAULT '',
   config_json TEXT NOT NULL,
   created_at TEXT NOT NULL
+);
+CREATE TABLE IF NOT EXISTS settings (
+  key TEXT PRIMARY KEY,
+  value TEXT NOT NULL DEFAULT ''
 )
 `)
     return err
diff --git a/internal/storage/settings.go b/internal/storage/settings.go
new file mode 100644
index 0000000..2efeb63
--- /dev/null
+++ b/internal/storage/settings.go
@@ -0,0 +1,15 @@
+package storage
+
+import "database/sql"
+
+func LoadSetting(db *sql.DB, key string) (string, error) {
+    if db == nil {
+        return "", nil
+    }
+    var value string
+    err := db.QueryRow("SELECT value FROM settings WHERE key = ?", key).Scan(&value)
+    if err == sql.ErrNoRows {
+        return "", nil
+    }
+    return value, err
+}
diff --git a/internal/web/ui.go b/internal/web/ui.go
index 11f4e7a..53a8305 100644
--- a/internal/web/ui.go
+++ b/internal/web/ui.go
@@ -4281,12 +4281,18 @@ func (u *UI) actionSystemConfig(w http.ResponseWriter, r *http.Request) {
     if days, err := strconv.Atoi(strings.TrimSpace(r.FormValue("alarm_retention_days"))); err == nil && days >= 0 {
         if u.alarmCollector != nil {
             u.alarmCollector.SetRetention(days)
-            // Trigger immediate cleanup with new retention
             go u.alarmCollector.RunCleanup()
         }
-        msg := "告警保留已设为 " + strconv.Itoa(days) + " 天，立即生效"
+        // Persist to DB so it survives restart
+        if strings.TrimSpace(u.dbPath) != "" {
+            if store, err := storage.OpenSQLite(u.dbPath); err == nil {
+                store.DB().Exec("INSERT OR REPLACE INTO settings(key,value) VALUES('alarm_retention_days',?)", strconv.Itoa(days))
+                store.Close()
+            }
+        }
+        msg := "告警保留已设为 " + strconv.Itoa(days) + " 天，已持久化"
         if days == 0 {
-            msg = "告警将永久保留，立即生效"
+            msg = "告警将永久保留，已持久化"
         }
         u.renderSystemPage(w, r, http.StatusOK, msg, "")
         return
diff --git a/safesightd-linux-arm64 b/safesightd-linux-arm64
index 0d36f30..9be1b35 100644
Binary files a/safesightd-linux-arm64 and b/safesightd-linux-arm64 differ