diff --git a/apm-collector/apm-collector-ui/src/main/java/org/skywalking/apm/collector/ui/dao/InstanceH2DAO.java b/apm-collector/apm-collector-ui/src/main/java/org/skywalking/apm/collector/ui/dao/InstanceH2DAO.java
index 10922e752..db9945135 100644
--- a/apm-collector/apm-collector-ui/src/main/java/org/skywalking/apm/collector/ui/dao/InstanceH2DAO.java
+++ b/apm-collector/apm-collector-ui/src/main/java/org/skywalking/apm/collector/ui/dao/InstanceH2DAO.java
@@ -1,7 +1,6 @@
 package org.skywalking.apm.collector.ui.dao;
 
 import com.google.gson.JsonArray;
-import java.util.List;
 import org.skywalking.apm.collector.storage.define.register.InstanceDataDefine;
 import org.skywalking.apm.collector.storage.h2.dao.H2DAO;