diff --git a/model/alertrule.go b/model/alertrule.go
index 35ef273..d8277f1 100644
--- a/model/alertrule.go
+++ b/model/alertrule.go
@@ -54,12 +54,15 @@ func (u *Rule) Snapshot(server *Server) interface{} {
 	case "transfer_all":
 		src = server.State.NetOutTransfer + server.State.NetInTransfer
 	case "offline":
-		src = uint64(server.LastActive.Unix())
-	}
-	if u.Type == "offline" {
-		if uint64(time.Now().Unix())-src > 6 {
-			return struct{}{}
+		if server.LastActive.IsZero() {
+			src = 0
+		} else {
+			src = uint64(server.LastActive.Unix())
 		}
+	}
+
+	if u.Type == "offline" && uint64(time.Now().Unix())-src > 6 {
+		return struct{}{}
 	} else if (u.Max > 0 && src > u.Max) || (u.Min > 0 && src < u.Min) {
 		return struct{}{}
 	}
@@ -109,7 +112,7 @@ func (r *AlertRule) Check(points [][]interface{}) (int, string) {
 		if len(points) < num {
 			continue
 		}
-		for j := len(points) - 1; j >= 0; j-- {
+		for j := len(points) - 1; j >= 0 && len(points)-num <= j; j-- {
 			total++
 			if points[j][i] != nil {
 				fail++
diff --git a/service/alertmanager/alertmanager.go b/service/alertmanager/alertmanager.go
index 55788df..ad43299 100644
--- a/service/alertmanager/alertmanager.go
+++ b/service/alertmanager/alertmanager.go
@@ -84,6 +84,7 @@ func OnDeleteAlert(id uint64) {
 	for i := 0; i < len(alerts); i++ {
 		if alerts[i].ID == id {
 			alerts = append(alerts[:i], alerts[i+1:]...)
+			i--
 		}
 	}
 }
@@ -109,6 +110,7 @@ func OnDeleteNotification(id uint64) {
 	for i := 0; i < len(notifications); i++ {
 		if notifications[i].ID == id {
 			notifications = append(notifications[:i], notifications[i+1:]...)
+			i--
 		}
 	}
 }
@@ -155,17 +157,13 @@ func checkStatus() {
 					}, firstNotificationDelay+time.Minute*10)
 				}
 				if flag {
-					message := fmt.Sprintf("逮到咯，快去看看！服务器：%s(%s)，报警规则：%s，%s", server.Name, server.Host.IP, alert.Name, desc)
+					message := fmt.Sprintf("报警规则：%s，服务器：%s(%s)，%s，逮到咯，快去看看！", alert.Name, server.Name, server.Host.IP, desc)
 					go sendNotification(message)
 				}
 			}
 			// 清理旧数据
-			if max > 0 {
-				for k := 0; k < len(alertsStore[alert.ID][server.ID]); k++ {
-					if max < len(alertsStore[alert.ID][server.ID][k]) {
-						alertsStore[alert.ID][server.ID][k] = alertsStore[alert.ID][server.ID][k][len(alertsStore[alert.ID][server.ID][k])-max:]
-					}
-				}
+			if max > 0 && max < len(alertsStore[alert.ID][server.ID]) {
+				alertsStore[alert.ID][server.ID] = alertsStore[alert.ID][server.ID][len(alertsStore[alert.ID][server.ID])-max:]
 			}
 		}
 	}