diff --git a/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.c b/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.c
index 86ae01a..5dd38ec 100644
--- a/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.c
+++ b/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.c
@@ -178,6 +178,23 @@ const char *tls_bt_access_opt_2_str(uint8_t op)
     }
 }
 
+const char *tls_bt_sm_ioact_2_str(uint8_t ioact)
+{
+    switch(ioact)
+    {
+        CASE_RETURN_STR(BLE_SM_IOACT_NONE)
+        CASE_RETURN_STR(BLE_SM_IOACT_OOB)
+        CASE_RETURN_STR(BLE_SM_IOACT_INPUT)
+        CASE_RETURN_STR(BLE_SM_IOACT_DISP)
+        CASE_RETURN_STR(BLE_SM_IOACT_NUMCMP)
+        CASE_RETURN_STR(BLE_SM_IOACT_OOB_SC)
+        CASE_RETURN_STR(BLE_SM_IOACT_MAX_PLUS_ONE)
+        
+        default:
+            return "unknown io action type";
+    }
+}
+
 static void async_evt_func(struct ble_npl_event *ev)
 {
     ble_async_t *bat = (ble_async_t *)ev->arg;
diff --git a/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.h b/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.h
index 90c0e3c..3218f42 100644
--- a/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.h
+++ b/src/W800_SDK_v1.00.10/src/app/bleapp/wm_bt_util.h
@@ -56,6 +56,7 @@ const char *tls_bt_gap_evt_2_str(uint32_t event);
 const char *tls_bt_rc_2_str(uint32_t event);
 const char *tls_bt_addr_type_2_str(uint8_t addr_type);
 const char *tls_bt_access_opt_2_str(uint8_t op);
+const char *tls_bt_sm_ioact_2_str(uint8_t ioact);
 
 extern int tls_bt_util_init(void);
 extern int tls_bt_util_deinit(void);