diff --git a/im-center-server/src/main/java/cn/axzo/im/group/GroupManager.java b/im-center-server/src/main/java/cn/axzo/im/group/GroupManager.java
index ac9e7ff..0bb3380 100644
--- a/im-center-server/src/main/java/cn/axzo/im/group/GroupManager.java
+++ b/im-center-server/src/main/java/cn/axzo/im/group/GroupManager.java
@@ -64,7 +64,7 @@ public class GroupManager {
         groupSupport.log(0L, "create-group:preparing", request);
         Group savedGroup = groupDao.findByBizCode(request.getBizCode(), request.getGroupType(), true)
                 .orElse(null);
-        BizAssertions.assertNull(savedGroup == null || savedGroup.isDismissed(),
+        BizAssertions.assertTrue(savedGroup == null || savedGroup.isDismissed(),
                 String.format("群已经存在: %s", request.getName()));
         ImAccounts imAccounts = accountService.getOrCreateImAccounts(request.getPeople());
         String owner = imAccounts.findAccount(request.getOwner()).orElse(null);