diff --git a/README.md b/README.md
index 377cefb088a815117900b429cda74bc19099f41d..d36628a848381c9461bf0b9184d149316ddd1f0e 100644
--- a/README.md
+++ b/README.md
@@ -89,6 +89,7 @@ Json.fromJson[Person](json)
 
 - 说明
   - 支持普通类和样例类。
+  - 仅支持对主构造函数使用。   
   - 如果该类没有伴生对象，将生成一个伴生对象来存储`builder`方法和类。
 
 - 示例
diff --git a/README_EN.md b/README_EN.md
index acda009cb56049551696669af75de03458d14145..9fd97ba8bb3a76aa83d0e2cbdfebf55321dd253c 100644
--- a/README_EN.md
+++ b/README_EN.md
@@ -92,6 +92,7 @@ The `@builder` used to generate builder pattern for Scala classes.
 
 - Note
   - Support `case class` / `class`.
+  - Only support for **primary constructor**.  
   - If there is no companion object, one will be generated to store the `builder` class and method.
 
 - Example