diff --git a/pkg/scheduler/handler/ping.go b/pkg/scheduler/handler/ping.go
index a0c7a3992c..7e274caad7 100644
--- a/pkg/scheduler/handler/ping.go
+++ b/pkg/scheduler/handler/ping.go
@@ -42,7 +42,7 @@ func pingHandler(c *gin.Context) {
 	}
 	log.Infof("%v", c.Request.Body)
 
-	c.JSON(http.StatusOK, "pong")
+	c.String(http.StatusOK, "pong")
 }
 
 // switchHandler is a handler of switch service that just for