diff --git a/README.md b/README.md
index 171b5a0..375ca50 100644
--- a/README.md
+++ b/README.md
@@ -128,11 +128,17 @@ import (
 func main() {
   config := new(credentials.Config).
     SetType("oidc_role_arn").
+    // The ARN of OIDC provider
     SetOIDCProviderArn("OIDCProviderArn").
+    // The path of OIDC token file
     SetOIDCTokenFilePath("OIDCTokenFilePath").
+    // The ARN of role
+    SetRoleArn("RoleArn").
+    // The role session name
     SetRoleSessionName("RoleSessionName").
+    // Not required, The RAM policy document.
     SetPolicy("Policy").
-    SetRoleArn("RoleArn").
+    // Not required, limit the Valid time of STS Token
     SetSessionExpiration(3600)
   provider, err := credentials.NewCredential(config)
   if err != nil {