diff --git a/resourceschedule/ffrt/c/shared_mutex.h b/resourceschedule/ffrt/c/shared_mutex.h
index b295c54c21befa84de69dea15449bb2a69d7ac5b..bf7e2951d776fde032ad892f3586a621a1c4d551 100644
--- a/resourceschedule/ffrt/c/shared_mutex.h
+++ b/resourceschedule/ffrt/c/shared_mutex.h
@@ -42,7 +42,7 @@
  * @brief Initializes a rwlock.
  *
  * @param rwlock Indicates a pointer to the rwlock.
- * @param attr Indicates a pointer to the rwlock attribute.
+ * @param attr Indicates a pointer to the rwlock attribute, only supports default mode, set to null pointer.
  * @return Returns <b>ffrt_success</b> if the rwlock is initialized;
            returns <b>ffrt_error_inval</b> otherwise.
  * @since 18