diff --git a/static_core/plugins/ets/stdlib/escompat/json.ets b/static_core/plugins/ets/stdlib/escompat/json.ets
index dfdd97669cd9314964dd69ab769574470f2d65f8..66c598c550083a821a8cb868846603d61bca53f0 100644
--- a/static_core/plugins/ets/stdlib/escompat/json.ets
+++ b/static_core/plugins/ets/stdlib/escompat/json.ets
@@ -592,6 +592,7 @@ class JSONWriter {
 
     private readonly path = new Set<Object>()
     private buffer = new StringBuilder()
+    private cachedStrings = new Map<String, String>()
 
     constructor(replacer?: (key: String, value: NullishType) => NullishType, space?: String) {
         this.replacer = replacer
@@ -629,7 +630,13 @@ class JSONWriter {
         } else if (obj === undefined) {
             this.buffer.append("undefined")
         } else if (obj instanceof String) {
-            this.buffer.append(JSON.stringify(obj as String))
+            let key = obj as String
+            let value: String | undefined = this.cachedStrings.get(key)
+            if (value == undefined) {
+                value = JSON.stringify(key)
+                this.cachedStrings.set(key, value)
+            }
+            this.buffer.append(value)
         } else if (obj instanceof RegExpExecArray) {
             this.buffer.append(JSON.stringify((obj as RegExpExecArray).result))
         } else if(obj instanceof Tuple) {