diff --git a/workflow-engine-core/src/main/java/cn/axzo/workflow/core/service/impl/BpmnProcessTaskServiceImpl.java b/workflow-engine-core/src/main/java/cn/axzo/workflow/core/service/impl/BpmnProcessTaskServiceImpl.java
index 1148de677..d6fb057b9 100644
--- a/workflow-engine-core/src/main/java/cn/axzo/workflow/core/service/impl/BpmnProcessTaskServiceImpl.java
+++ b/workflow-engine-core/src/main/java/cn/axzo/workflow/core/service/impl/BpmnProcessTaskServiceImpl.java
@@ -560,7 +560,7 @@ public class BpmnProcessTaskServiceImpl implements BpmnProcessTaskService {
 
             BpmnTaskDelegateAssigner assigner = Objects.nonNull(assginerSnapshot) ?
                     (BpmnTaskDelegateAssigner) assginerSnapshot.getValue() : null;
-            if (!vo.getAssignee().contains(TASK_ASSIGNEE_SKIP_FLAT)) {
+            if (StringUtils.hasLength(vo.getAssignee()) && !vo.getAssignee().contains(TASK_ASSIGNEE_SKIP_FLAT)) {
                 vo.setAssignee(Objects.isNull(assigner) ? "" : assigner.getAssignee());
             }
             vo.setAssigneeSnapshot(assigner);