diff --git a/powerjob-server/powerjob-server-remote/src/main/java/tech/powerjob/server/remote/worker/WorkerClusterQueryService.java b/powerjob-server/powerjob-server-remote/src/main/java/tech/powerjob/server/remote/worker/WorkerClusterQueryService.java
index 5cb48004..da555c0b 100644
--- a/powerjob-server/powerjob-server-remote/src/main/java/tech/powerjob/server/remote/worker/WorkerClusterQueryService.java
+++ b/powerjob-server/powerjob-server-remote/src/main/java/tech/powerjob/server/remote/worker/WorkerClusterQueryService.java
@@ -1,14 +1,14 @@
 package tech.powerjob.server.remote.worker;
 
+import com.google.common.collect.Lists;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
 import tech.powerjob.common.model.DeployedContainerInfo;
 import tech.powerjob.server.common.module.WorkerInfo;
 import tech.powerjob.server.extension.WorkerFilter;
 import tech.powerjob.server.persistence.remote.model.JobInfoDO;
 import tech.powerjob.server.remote.server.redirector.DesignateServer;
-import com.google.common.collect.Lists;
-import lombok.extern.slf4j.Slf4j;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.stereotype.Service;
 
 import java.util.Collections;
 import java.util.List;
@@ -34,6 +34,7 @@ public class WorkerClusterQueryService {
 
     /**
      * get worker for job
+     *
      * @param jobInfo job
      * @return worker cluster info, sorted by metrics desc
      */
@@ -44,7 +45,7 @@ public class WorkerClusterQueryService {
         workers.removeIf(workerInfo -> filterWorker(workerInfo, jobInfo));
 
         // 按健康度排序
-        workers.sort((o1, o2) -> o2 .getSystemMetrics().calculateScore() - o1.getSystemMetrics().calculateScore());
+        workers.sort((o1, o2) -> o2.getSystemMetrics().calculateScore() - o1.getSystemMetrics().calculateScore());
 
         // 限定集群大小（0代表不限制）
         if (!workers.isEmpty() && jobInfo.getMaxWorkerCount() > 0 && workers.size() > jobInfo.getMaxWorkerCount()) {
@@ -56,12 +57,13 @@ public class WorkerClusterQueryService {
     @DesignateServer
     public List<WorkerInfo> getAllWorkers(Long appId) {
         List<WorkerInfo> workers = Lists.newLinkedList(getWorkerInfosByAppId(appId).values());
-        workers.sort((o1, o2) -> o2 .getSystemMetrics().calculateScore() - o1.getSystemMetrics().calculateScore());
+        workers.sort((o1, o2) -> o2.getSystemMetrics().calculateScore() - o1.getSystemMetrics().calculateScore());
         return workers;
     }
 
     /**
      * get all alive workers
+     *
      * @param appId appId
      * @return alive workers
      */
@@ -71,8 +73,22 @@ public class WorkerClusterQueryService {
         return workers;
     }
 
+    /**
+     * Gets worker info by address.
+     *
+     * @param appId   the app id
+     * @param address the address
+     * @return the worker info by address
+     */
     public Optional<WorkerInfo> getWorkerInfoByAddress(Long appId, String address) {
-        return Optional.ofNullable(getWorkerInfosByAppId(appId).get(address));
+        // this may cause NPE while address value is null .
+        //return Optional.ofNullable(getWorkerInfosByAppId(appId).get(address));
+        final Map<String, WorkerInfo> workerInfosByAppId = getWorkerInfosByAppId(appId);
+        //add null check for both workerInfos Map and  address
+        if (null != workerInfosByAppId && null != address) {
+            return Optional.ofNullable(workerInfosByAppId.get(address));
+        }
+        return Optional.empty();
     }
 
     public Map<Long, ClusterStatusHolder> getAppId2ClusterStatus() {
@@ -81,7 +97,8 @@ public class WorkerClusterQueryService {
 
     /**
      * 获取某个应用容器的部署情况
-     * @param appId 应用ID
+     *
+     * @param appId       应用ID
      * @param containerId 容器ID
      * @return 部署情况
      */
@@ -104,8 +121,9 @@ public class WorkerClusterQueryService {
 
     /**
      * filter invalid worker for job
+     *
      * @param workerInfo worker info
-     * @param jobInfo job info
+     * @param jobInfo    job info
      * @return filter this worker when return true
      */
     private boolean filterWorker(WorkerInfo workerInfo, JobInfoDO jobInfo) {