diff --git a/src/generators/extend.ts b/src/generators/extend.ts
index 884a526..d94fff6 100644
--- a/src/generators/extend.ts
+++ b/src/generators/extend.ts
@@ -6,6 +6,10 @@ import { declMapping } from '../config';
 import { GeneratorResult, TsGenConfig, TsHelperConfig } from '..';
 
 const debug = debuglog('egg-ts-helper#generators_extend');
+const hasExportWithoutDefault = (filePath: string) => {
+  const result = utils.findExportNode(fs.readFileSync(filePath, 'utf-8'));
+  return !result.exportDefaultNode;
+};
 
 export default function ExtendGenerator(config: TsGenConfig, baseConfig: TsHelperConfig) {
   const fileList = config.file ? [ config.file ] : config.fileList;
@@ -41,7 +45,9 @@ export default function ExtendGenerator(config: TsGenConfig, baseConfig: TsHelpe
 
     // get import info
     const moduleName = `Extend${interfaceEnvironment}${interfaceName}`;
-    const importContext = utils.getImportStr(config.dtsDir, f, moduleName);
+
+    const useImportStar = hasExportWithoutDefault(f);
+    const importContext = utils.getImportStr(config.dtsDir, f, moduleName, useImportStar);
     tsList.push({
       dist,
       content:
diff --git a/test/fixtures/app/app/extend/helper.ts b/test/fixtures/app/app/extend/helper.ts
index f1159be..31c3840 100644
--- a/test/fixtures/app/app/extend/helper.ts
+++ b/test/fixtures/app/app/extend/helper.ts
@@ -1,13 +1,7 @@
-let helper;
+export function isCool() {
+  console.info('is Cool');
+}
 
-helper = {
-  isCool() {
-    console.info('is Cool');
-  },
-
-  isNotCool() {
-    console.info('is not Cool');
-  },
-};
-
-export default helper;
+export function isNotCool() {
+  console.info('is not Cool');
+}
diff --git a/test/generators/extend.test.ts b/test/generators/extend.test.ts
index ce3722d..b6cf355 100644
--- a/test/generators/extend.test.ts
+++ b/test/generators/extend.test.ts
@@ -49,7 +49,7 @@ describe('generators/extend.test.ts', () => {
   it('should works without error with helper', () => {
     const result = triggerGenerator('extend', appDir, 'helper.ts');
     const item = result[0];
-    assert(item.content!.includes('../../../app/extend/helper'));
+    assert(item.content!.includes('import * as ExtendIHelper from \'../../../app/extend/helper\''));
     assert(item.content!.includes('type ExtendIHelperType = typeof ExtendIHelper'));
     assert(item.content!.includes('interface IHelper extends ExtendIHelperType { }'));
   });
@@ -58,7 +58,7 @@ describe('generators/extend.test.ts', () => {
     const result = triggerGenerator('extend', appDir, 'application.unittest.ts');
     const item = result[0];
     assert(item.dist === path.resolve(appDir, './typings/app/extend/application.unittest.d.ts'));
-    assert(item.content!.includes('../../../app/extend/application.unittest'));
+    assert(item.content!.includes('import ExtendUnittestApplication from \'../../../app/extend/application.unittest\''));
     assert(item.content!.includes('type ExtendUnittestApplicationType = typeof ExtendUnittestApplication;'));
     assert(item.content!.includes('interface Application extends ExtendUnittestApplicationType { }'));
   });