diff --git a/service/dbmService.go b/service/dbmService.go
index 6610a54..3eb7f79 100644
--- a/service/dbmService.go
+++ b/service/dbmService.go
@@ -240,11 +240,11 @@ func GetDBTableDesc(req *proto.GetDBTableDescReq, userId int) (*proto.SQLResult,
 
 func DelDBMMap() {
 	dao.DBMMapRWMutex.Lock()
-	defer dao.DBMMapRWMutex.Unlock()
 	cur := worker.GetCurrentTimestamp()
 	for k, v := range dao.DBMMap {
-		if cur-v.LastUserTime < proto.DBMMap_Max_Keep_Time {
+		if (cur - v.LastUserTime) > proto.DBMMap_Max_Keep_Time {
 			delete(dao.DBMMap, k) //删除
 		}
 	}
+	dao.DBMMapRWMutex.Unlock()
 }