diff --git a/src/main/java/com/kimgo/wepush/controller/HeartbeatController.java b/src/main/java/com/kimgo/wepush/controller/HeartbeatController.java
index 05c1515..86cc75e 100644
--- a/src/main/java/com/kimgo/wepush/controller/HeartbeatController.java
+++ b/src/main/java/com/kimgo/wepush/controller/HeartbeatController.java
@@ -5,6 +5,8 @@ import com.kimgo.wepush.model.DeviceInfo;
 import com.kimgo.wepush.response.ServerResponseEntity;
 import com.kimgo.wepush.service.HeartBeatService;
 import jakarta.validation.Valid;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
@@ -15,6 +17,7 @@ import org.springframework.web.bind.annotation.RestController;
 public class HeartbeatController {
     @Autowired
     private HeartBeatService heartBeatService;
+    private final Logger logger = LoggerFactory.getLogger(CallerController.class);
 
     @PostMapping("/heartbeat")
     public ServerResponseEntity receiveHeartbeat(@RequestHeader("accessToken") String accessToken,
@@ -25,6 +28,7 @@ public class HeartbeatController {
             return ServerResponseEntity.fail("accessToken cannot be empty.");
         }
         if (deviceInfo == null || deviceInfo.hasInvalidFields()){
+            logger.info("DeviceInfo: {}",deviceInfo.toString());
             return ServerResponseEntity.fail("json body value error.");
         }
         return heartBeatService.handleHeartbeatSignal(accessToken,deviceInfo);
diff --git a/src/main/java/com/kimgo/wepush/model/DeviceInfoDAO.java b/src/main/java/com/kimgo/wepush/model/DeviceInfoDAO.java
index 97ccb8f..4e49afc 100644
--- a/src/main/java/com/kimgo/wepush/model/DeviceInfoDAO.java
+++ b/src/main/java/com/kimgo/wepush/model/DeviceInfoDAO.java
@@ -12,6 +12,7 @@ public class DeviceInfoDAO {
     @TableId(type = IdType.AUTO)
     private Integer id;
     private int isMonitored;
+    //设备超时时间，单位秒
     private long timeOutPeriod;
     private String deviceBrand;
     private String androidVersion;
diff --git a/src/main/java/com/kimgo/wepush/service/HeartBeatService.java b/src/main/java/com/kimgo/wepush/service/HeartBeatService.java
index 8957eed..2c7664e 100644
--- a/src/main/java/com/kimgo/wepush/service/HeartBeatService.java
+++ b/src/main/java/com/kimgo/wepush/service/HeartBeatService.java
@@ -52,7 +52,7 @@ public class HeartBeatService {
 
         UpdateWrapper<DeviceInfoDAO> updateWrapper = new UpdateWrapper<>();
         updateWrapper.eq("sn", deviceInfo.getSN());
-        updateWrapper.set("last_online_time", currentTimeMillis); // 设置新的 accessToken
+        updateWrapper.set("last_online_time", currentTimeMillis);
 
         int result = deviceInfoDAOMapper.update(null, updateWrapper);
         if (result > 0) {
@@ -86,11 +86,11 @@ public class HeartBeatService {
         try {
             DeviceInfoDAO deviceInfoDAO = deviceInfoDAOMapper.selectOne(queryWrapper);
             if (deviceInfoDAO != null) {
-                logger.info("Data is queried in the database based on the device id");
+                logger.info("Data is queried in the database based on the SN");
                 return deviceInfoDAO;
             }
         } catch (Exception e) {
-            logger.error("Error querying device info by android ID", e);
+            logger.error("Error querying device info by SN", e);
         }
         return null;
     }
diff --git a/src/main/java/com/kimgo/wepush/service/MonitorService.java b/src/main/java/com/kimgo/wepush/service/MonitorService.java
index 89a6cb6..1a0ff70 100644
--- a/src/main/java/com/kimgo/wepush/service/MonitorService.java
+++ b/src/main/java/com/kimgo/wepush/service/MonitorService.java
@@ -44,11 +44,17 @@ public class MonitorService {
                     continue;
                 }
                 long currentTimeMillis = System.currentTimeMillis();
-                if (currentTimeMillis - device.getLastOnlineTime() > device.getTimeOutPeriod()) {
+                long timeDifferenceMillis = currentTimeMillis - device.getLastOnlineTime();
+                long timeDifferenceSeconds = timeDifferenceMillis / 1000;
+                if (timeDifferenceSeconds > device.getTimeOutPeriod()) {
+                    logger.info("currentTimeMillis: {},device LastOnlineTime: {},时间差: {},设备超时时间: {}",currentTimeMillis,
+                            device.getLastOnlineTime(),timeDifferenceSeconds,device.getTimeOutPeriod());
                     updateStatus(device, 0); // 设备离线
+                    logger.info("Update the device status to offline.");
                     sendNotification(device);
                 } else {
                     updateStatus(device, 1); // 设备在线
+                    logger.info("update the device status to online.");
                 }
             } catch (Exception e) {
                 logger.error("Error processing device with SN " + device.getSN(), e);
diff --git a/src/test/java/com/kimgo/wepush/service/HeartBeatServiceTest.java b/src/test/java/com/kimgo/wepush/service/HeartBeatServiceTest.java
index c42410a..02250be 100644
--- a/src/test/java/com/kimgo/wepush/service/HeartBeatServiceTest.java
+++ b/src/test/java/com/kimgo/wepush/service/HeartBeatServiceTest.java
@@ -19,6 +19,5 @@ class HeartBeatServiceTest {
     @Test
     void addDeviceInfo() {
         DeviceInfo deviceInfo = new DeviceInfo();
-        deviceInfo.setDeviceModel("Model C");
     }
 }
\ No newline at end of file