diff --git a/powerjob-common/src/main/java/tech/powerjob/common/serialize/JsonUtils.java b/powerjob-common/src/main/java/tech/powerjob/common/serialize/JsonUtils.java
index 985b8df9..085da18c 100644
--- a/powerjob-common/src/main/java/tech/powerjob/common/serialize/JsonUtils.java
+++ b/powerjob-common/src/main/java/tech/powerjob/common/serialize/JsonUtils.java
@@ -32,6 +32,9 @@ public class JsonUtils {
     }
 
     public static String toJSONString(Object obj) {
+        if (obj instanceof String) {
+            return (String) obj;
+        }
         try {
             return JSON_MAPPER.writeValueAsString(obj);
         }catch (Exception e) {
@@ -41,6 +44,9 @@ public class JsonUtils {
     }
 
     public static String toJSONStringUnsafe(Object obj) {
+        if (obj instanceof String) {
+            return (String) obj;
+        }
         try {
             return JSON_MAPPER.writeValueAsString(obj);
         }catch (Exception e) {