diff --git a/README.md b/README.md
index 15bbff8..b8071e4 100644
--- a/README.md
+++ b/README.md
@@ -67,6 +67,7 @@ For detailed API documentation, please see [docs/api.md](docs/api.md)
 - [ ] Add frpc instance log display API
 - [ ] Fix random database lock when processing logs
 - [ ] Add frpc createdBy storage and display
+- [x] Fix backend can still start frpc instance when it is already running
 
 ## License
 
diff --git a/docs/api.md b/docs/api.md
index db8f255..743f74f 100644
--- a/docs/api.md
+++ b/docs/api.md
@@ -1138,7 +1138,7 @@ X-Timestamp: 1704067200000
 | X-Token | string | Yes | Authentication token |
 | X-Timestamp | int64 | Yes | Client timestamp in milliseconds |
 
-**Response (admin/superuser):**
+**Response:**
 ```json
 {
   "success": true,
@@ -1147,33 +1147,9 @@ X-Timestamp: 1704067200000
     {
       "instanceID": 1,
       "name": "my_frpc",
-      "serverAddr": "127.0.0.1",
-      "serverPort": "7000",
-      "auth.method": "token",
-      "bootAtStart": true,
-      "runUser": "root",
-      "configPath": "./configs/superfrpc_user_my_frpc.toml",
       "createdAt": "2024-01-01T00:00:00Z",
-      "createdBy": "admin"
-    }
-  ]
-}
-```
-
-**Response (visitor):**
-```json
-{
-  "success": true,
-  "message": "instances retrieved successfully",
-  "data": [
-    {
-      "instanceID": 1,
-      "name": "my_frpc",
-      "bootAtStart": true,
-      "runUser": "root",
-      "configPath": "./configs/superfrpc_user_my_frpc.toml",
-      "createdAt": "2024-01-01T00:00:00Z",
-      "createdBy": "admin"
+      "createdBy": "admin",
+      "isRunning": true
     }
   ]
 }
@@ -1183,16 +1159,9 @@ X-Timestamp: 1704067200000
 |-------|------|-------------|
 | instanceID | int | Instance ID |
 | name | string | Instance name |
-| serverAddr | string | frps server address (admin/superuser only) |
-| serverPort | string | frps server port (admin/superuser only) |
-| auth.method | string | Authentication method (admin/superuser only) |
-| bootAtStart | bool | Auto-start on system boot |
-| runUser | string | User to run the frpc instance as |
-| configPath | string | Path to the configuration file |
 | createdAt | string | Instance creation time (ISO 8601 format) |
 | createdBy | string | Username of the user who created this instance |
-
-> Note: Visitor users do not see sensitive information (serverAddr, serverPort, auth.method).
+| isRunning | bool | Instance running status: true (running) or false (stopped) |
 
 ---
 
diff --git a/frpAct.go b/frpAct.go
index ae834d1..b3e625b 100644
--- a/frpAct.go
+++ b/frpAct.go
@@ -539,13 +539,6 @@ func ListInstancesHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	userType, err := GetUserType(userID)
-	if err != nil {
-		postLog.Error(fmt.Sprintf("[ListInstancesHandler] Failed to get user type: %v", err))
-		SendErrorResponse(w, http.StatusInternalServerError, "Failed to get user type")
-		return
-	}
-
 	instances, err := GetUserInstances(userID)
 	if err != nil {
 		postLog.Error(fmt.Sprintf("[ListInstancesHandler] Failed to get user instances: %v", err))
@@ -556,32 +549,18 @@ func ListInstancesHandler(w http.ResponseWriter, r *http.Request) {
 	instanceList := make([]map[string]interface{}, len(instances))
 	for i, inst := range instances {
 		instanceData := map[string]interface{}{
-			"instanceID":  inst.ID,
-			"name":        inst.Name,
-			"bootAtStart": inst.BootAtStart,
-			"runUser":     inst.RunUser,
-			"configPath":  inst.ConfigPath,
-			"createdAt":   inst.CreatedAt,
-			"createdBy":   inst.CreatedBy,
-		}
-
-		if userType == "admin" || userType == "superuser" {
-			serverAddr, err := getKeyText(inst.ConfigPath, "serverAddr", "")
-			serverPort, err := getKeyText(inst.ConfigPath, "serverPort", "")
-			authMethod, err := getKeyText(inst.ConfigPath, "auth.method", "")
-			if err != nil {
-				postLog.Error(fmt.Sprintf("[ListInstancesHandler] Failed to read config for instance %d: %v", inst.ID, err))
-			}
-			instanceData["serverAddr"] = serverAddr
-			instanceData["serverPort"] = serverPort
-			instanceData["auth_method"] = authMethod
+			"instanceID": inst.ID,
+			"name":       inst.Name,
+			"createdAt":  inst.CreatedAt,
+			"createdBy":  inst.CreatedBy,
+			"isRunning":  IsInstanceRunning(inst.ID),
 		}
 
 		instanceList[i] = instanceData
 	}
 
 	SendSuccessResponse(w, "Instances retrieved successfully", instanceList)
-	postLog.Info(fmt.Sprintf("[ListInstancesHandler] Retrieved %d instances for user %d (type: %s)", len(instances), userID, userType))
+	postLog.Info(fmt.Sprintf("[ListInstancesHandler] Retrieved %d instances for user %d", len(instances), userID))
 }
 
 func StartInstanceHandler(w http.ResponseWriter, r *http.Request) {