diff --git a/app/services/cmd_service/cmd_service.go b/app/services/cmd_service/cmd_service.go
index 946cae5..7c6f532 100644
--- a/app/services/cmd_service/cmd_service.go
+++ b/app/services/cmd_service/cmd_service.go
@@ -51,7 +51,7 @@ func Add(request *backend.CmdAddRequest) (err error) {
 	_ = mapstructure.Decode(request, &db)
 	db.Status = common.CMD_STATUS_STOP
 	if db.MatchJson == "" {
-		db.MatchJson = "{}"
+		db.MatchJson = "null"
 	}
 	_, err = croncmdmodel.GetInstance().GetDb().InsertOne(db)
 	return