diff --git a/components/net/freemodbus/port/user_mb_app.h b/components/net/freemodbus/port/user_mb_app.h
index fd2b203194..864c3860bf 100644
--- a/components/net/freemodbus/port/user_mb_app.h
+++ b/components/net/freemodbus/port/user_mb_app.h
@@ -24,7 +24,6 @@
 #define          S_CO_RESERVE                     0
 /* salve mode: discrete's all address */
 #define          S_DI_RESERVE                     0
-/* slave mode: holding register"s startup address */
 
 /* -----------------------Master Defines -------------------------------------*/
 #define M_DISCRETE_INPUT_START        0