diff --git a/README.md b/README.md
index fb473aa..d002e24 100644
--- a/README.md
+++ b/README.md
@@ -39,8 +39,8 @@ RuCaptcha.configure do
   # Store Captcha code where, this config more like Rails config.cache_store
   # default: Read config info from `Rails.application.config.cache_store`
   # But RuCaptcha requirements cache_store not in [:null_store, :memory_store, :file_store]
-  # 默认：将会从 Rails 配置的 cache_store 里面读取相同的配置信息
-  # 但如果是 [:null_store, :memory_store, :file_store] 之类的，不行
+  # 默认：会从 Rails 配置的 cache_store 里面读取相同的配置信息，用于存储验证码字符
+  # 但如果是 [:null_store, :memory_store, :file_store] 之类的，你可以通过下面的配置项单独给 RuCaptcha 配置 cache_store
   self.cache_store = :mem_cache_store
 end
 ```