diff --git a/packages/gem-analyzer/src/index.ts b/packages/gem-analyzer/src/index.ts
index fa0dcd98..99dd4c86 100644
--- a/packages/gem-analyzer/src/index.ts
+++ b/packages/gem-analyzer/src/index.ts
@@ -1,4 +1,4 @@
-import type { SourceFile, ClassDeclaration } from 'ts-morph';
+import type { SourceFile, ClassDeclaration, Project } from 'ts-morph';
 import { camelToKebabCase } from '@mantou/gem/lib/utils';
 
 import { getJsDoc } from './lib/utils';
@@ -65,6 +65,7 @@ export interface ElementDetail {
   slots: string[];
   parts: string[];
   cssStates: string[];
+  extend?: ElementDetail;
 }
 
 const shadowDecoratorName = ['shadow'];
@@ -79,7 +80,35 @@ const eventDecoratorName = ['emitter', 'globalemitter'];
 const globalEventDecoratorName = ['globalemitter'];
 const lifecyclePopsOrMethods = ['state', 'willMount', 'render', 'mounted', 'shouldUpdate', 'updated', 'unmounted'];
 
-export const parseElement = (declaration: ClassDeclaration) => {
+async function getExtendsClassDetail(className: string, sourceFile: SourceFile, project?: Project) {
+  const currentFile = sourceFile.getFilePath();
+  const isAbsFilePath = currentFile.startsWith('/');
+  if (!isAbsFilePath || !project) return;
+  const fileSystem = project.getFileSystem();
+  const importDeclaration = sourceFile.getImportDeclaration(
+    (desc) =>
+      !!desc
+        .getNamedImports()
+        .map((e) => e.getText())
+        .find((e) => e.includes(className)),
+  );
+  if (!importDeclaration) return;
+  const depPath = importDeclaration.getModuleSpecifierValue();
+  if (!depPath.startsWith('.')) return;
+  const { pathname } = new URL(`${depPath}.ts`, `gem:${currentFile}`);
+  if (project.getSourceFile(pathname)) return;
+  project.createSourceFile(pathname, '');
+  try {
+    const text = await fileSystem.readFile(pathname);
+    const file = project.createSourceFile(pathname, text, { overwrite: true });
+    const classDeclaration = file.getClass(className);
+    return classDeclaration && parseElement(classDeclaration, file, project);
+  } catch {
+    return;
+  }
+}
+
+export const parseElement = async (declaration: ClassDeclaration, file: SourceFile, project?: Project) => {
   const detail: ElementDetail = {
     name: '',
     shadow: false,
@@ -104,6 +133,7 @@ export const parseElement = (declaration: ClassDeclaration) => {
   declaration.getJsDocs().forEach((jsDoc) => appendElementDesc(jsDoc.getCommentText()));
 
   if (className && constructorExtendsName) {
+    detail.extend = await getExtendsClassDetail(constructorExtendsName, file, project);
     detail.constructorName = className;
     detail.constructorExtendsName = constructorExtendsName;
     if (constructor) {
@@ -240,7 +270,7 @@ export const parseElement = (declaration: ClassDeclaration) => {
   return detail;
 };
 
-export const getElements = (file: SourceFile) => {
+export const getElements = async (file: SourceFile, project?: Project) => {
   const result: ElementDetail[] = [];
   for (const declaration of file.getClasses()) {
     // need support other decorators?
@@ -263,7 +293,7 @@ export const getElements = (file: SourceFile) => {
         ?.getCommentText();
     if (elementTag) {
       const detail: ElementDetail = {
-        ...parseElement(declaration),
+        ...(await parseElement(declaration, file, project)),
         name: elementTag,
         shadow: !!shadowDeclaration,
       };
@@ -283,7 +313,7 @@ export interface ExportDetail {
   description?: string;
 }
 
-export const getExports = (file: SourceFile) => {
+export const getExports = async (file: SourceFile) => {
   const result: ExportDetail[] = [];
 
   for (const [name, declarations] of file.getExportedDeclarations()) {
diff --git a/packages/gem-book/src/plugins/api.ts b/packages/gem-book/src/plugins/api.ts
index 8dcfb761..6f76bbcd 100644
--- a/packages/gem-book/src/plugins/api.ts
+++ b/packages/gem-book/src/plugins/api.ts
@@ -20,6 +20,8 @@ const {
   adoptedStyle,
   BoundaryCSSState,
   effect,
+  kebabToCamelCase,
+  camelToKebabCase,
 } = Gem;
 
 const styles = createCSSSheet(css`
@@ -66,15 +68,26 @@ class _GbpApiElement extends GemBookPluginElement {
       useInMemoryFileSystem: true,
       compilerOptions: { target: ts.ScriptTarget.ESNext },
     });
+    const fileSystem = project.getFileSystem();
+    fileSystem.readFile = async (filePath: string) => {
+      const url = Utils.getRemoteURL(filePath);
+      return (await fetch(url)).text();
+    };
     const file = project.createSourceFile(this.src, text);
-    return { elements: getElements(file), exports: getExports(file) };
+    return { elements: await getElements(file, project), exports: await getExports(file) };
   };
 
-  #renderHeader = (headingLevel: number, text: string, name: string) => {
-    return `${'#'.repeat(headingLevel + this.#headingLevel - 1)} ${text} {#${`${name}-${text}`.replaceAll(
-      ' ',
-      '-',
-    )}}\n\n`;
+  #renderHeader = (text: string, extText: string, root?: ElementDetail) => {
+    const baseLevel = root?.extend ? 2 : 1;
+    const headingLevel = extText === text ? baseLevel - 1 : baseLevel;
+    const level = '#'.repeat(headingLevel + this.#headingLevel - 1);
+    const title = root?.extend ? `\`${extText}\` ${text}` : text;
+    const hash = `${[extText === text ? '' : extText, text]
+      .map((e) => kebabToCamelCase(e).replaceAll(' ', ''))
+      .map((e) => camelToKebabCase(e).replace('-', ''))
+      .filter((e) => e)
+      .join('-')}`;
+    return `${level} ${title} {#${hash}}\n\n`;
   };
 
   #renderCode = (s = '', deprecated?: boolean) => {
@@ -93,10 +106,9 @@ class _GbpApiElement extends GemBookPluginElement {
     return text;
   };
 
-  #renderElement = (detail: ElementDetail) => {
+  #renderElement = (detail: ElementDetail, root = detail): string => {
     const {
       shadow,
-      name: eleName,
       description: eleDescription = '',
       constructorName,
       constructorExtendsName,
@@ -109,9 +121,15 @@ class _GbpApiElement extends GemBookPluginElement {
       cssStates,
       parts,
       slots,
+      extend,
     } = detail;
+
     let text = '';
 
+    if (root.extend) {
+      text += this.#renderHeader(constructorName, constructorName);
+    }
+
     text += eleDescription + '\n\n';
     if (constructorExtendsName) {
       if (shadow) {
@@ -121,7 +139,7 @@ class _GbpApiElement extends GemBookPluginElement {
     }
 
     if (constructorName && constructorParams.length) {
-      text += this.#renderHeader(1, `Constructor \`${constructorName}()\``, eleName);
+      text += this.#renderHeader(`Constructor \`${constructorName}()\``, constructorName, root);
       text += this.#renderTable(
         constructorParams,
         ['Params', 'Type'].concat(constructorParams.some((e) => e.description) ? 'Description' : []),
@@ -133,7 +151,7 @@ class _GbpApiElement extends GemBookPluginElement {
       );
     }
     if (staticProperties.length) {
-      text += this.#renderHeader(1, 'Static Properties', eleName);
+      text += this.#renderHeader('Static Properties', constructorName, root);
       text += this.#renderTable(
         staticProperties,
         ['Property', 'Type'].concat(constructorParams.some((e) => e.description) ? 'Description' : []),
@@ -145,7 +163,7 @@ class _GbpApiElement extends GemBookPluginElement {
       );
     }
     if (staticMethods.length) {
-      text += this.#renderHeader(1, 'Static Methods', eleName);
+      text += this.#renderHeader('Static Methods', constructorName, root);
       text += this.#renderTable(
         staticMethods,
         ['Method', 'Type'].concat(constructorParams.some((e) => e.description) ? 'Description' : []),
@@ -157,7 +175,7 @@ class _GbpApiElement extends GemBookPluginElement {
       );
     }
     if (properties.length) {
-      text += this.#renderHeader(1, 'Instance Properties', eleName);
+      text += this.#renderHeader('Instance Properties', constructorName, root);
       text += this.#renderTable(
         properties.filter(({ slot, cssState, part, isRef }) => !slot && !cssState && !part && !isRef),
         ['Property(Attribute)', 'Reactive', 'Type'].concat(
@@ -174,7 +192,7 @@ class _GbpApiElement extends GemBookPluginElement {
     }
 
     if (methods.length) {
-      text += this.#renderHeader(1, 'Instance Methods', eleName);
+      text += this.#renderHeader('Instance Methods', constructorName, root);
       text += this.#renderTable(
         methods.filter(({ event }) => !event),
         ['Method', 'Type'].concat(constructorParams.some((e) => e.description) ? 'Description' : []),
@@ -193,7 +211,7 @@ class _GbpApiElement extends GemBookPluginElement {
       { type: 'CSS State', value: cssStates },
     ];
     if (otherRows.some(({ value }) => !!value.length)) {
-      text += this.#renderHeader(1, 'Other', eleName);
+      text += this.#renderHeader('Other', constructorName, root);
       text += this.#renderTable(
         otherRows.filter(({ value }) => !!value.length),
         ['Type', 'Value'],
@@ -201,7 +219,11 @@ class _GbpApiElement extends GemBookPluginElement {
       );
     }
 
-    return Utils.parseMarkdown(text);
+    if (extend) {
+      text += this.#renderElement(extend, detail) + '\n\n';
+    }
+
+    return text;
   };
 
   #renderExports = (exports: ExportDetail[]) => {
@@ -249,6 +271,6 @@ class _GbpApiElement extends GemBookPluginElement {
     if (!elements) return html`<div class="loading">API Loading...</div>`;
     const renderElements = this.name ? elements.filter(({ name }) => this.name === name) : elements;
     if (!renderElements.length && exports) return html`${this.#renderExports(exports)}`;
-    return html`${renderElements.map(this.#renderElement)}`;
+    return html`${renderElements.map((detail) => Utils.parseMarkdown(this.#renderElement(detail)))}`;
   };
 }
diff --git a/packages/gem-port/src/common.ts b/packages/gem-port/src/common.ts
index abda5f20..75e8d405 100644
--- a/packages/gem-port/src/common.ts
+++ b/packages/gem-port/src/common.ts
@@ -28,13 +28,13 @@ export function getElementPathList(elementsDir: string) {
 
 const elementCache: Record<string, ElementDetail[] | undefined> = {};
 const project = new Project({ useInMemoryFileSystem: true });
-export function getFileElements(elementFilePath: string) {
-  return (
-    elementCache[elementFilePath] ||
-    (elementCache[elementFilePath] = getElements(
-      project.createSourceFile(elementFilePath, readFileSync(elementFilePath, { encoding: 'utf-8' })),
-    ))
-  );
+export async function getFileElements(elementFilePath: string) {
+  if (!elementCache[elementFilePath]) {
+    const text = readFileSync(elementFilePath, { encoding: 'utf-8' });
+    const file = project.createSourceFile(elementFilePath, text);
+    elementCache[elementFilePath] = await getElements(file);
+  }
+  return elementCache[elementFilePath];
 }
 
 export function getComponentName(tag: string) {
diff --git a/packages/gem-port/src/index.ts b/packages/gem-port/src/index.ts
index df346262..56d3732a 100644
--- a/packages/gem-port/src/index.ts
+++ b/packages/gem-port/src/index.ts
@@ -22,10 +22,12 @@ program
   .option('-o, --outdir <path>', `specify out dir`, (outdir: string) => (cliOptions.outDir = outdir))
   .option('--svelte-ns <ns>', `specify svelte element namespace`, (ns: string) => (cliOptions.svelteNs = ns))
   .arguments('<dir>')
-  .action((dir: string) => {
-    compileReact(dir, path.resolve(cliOptions.outDir, 'react'));
-    generateVue(dir, path.resolve(cliOptions.outDir, 'vue'));
-    compileSvelte(dir, path.resolve(cliOptions.outDir, 'svelte'), cliOptions.svelteNs);
+  .action(async (dir: string) => {
+    await Promise.all([
+      compileReact(dir, path.resolve(cliOptions.outDir, 'react')),
+      generateVue(dir, path.resolve(cliOptions.outDir, 'vue')),
+      compileSvelte(dir, path.resolve(cliOptions.outDir, 'svelte'), cliOptions.svelteNs),
+    ]);
     process.exit(0);
   });
 
diff --git a/packages/gem-port/src/react.ts b/packages/gem-port/src/react.ts
index d03239b1..87dd197e 100644
--- a/packages/gem-port/src/react.ts
+++ b/packages/gem-port/src/react.ts
@@ -7,8 +7,8 @@ import {
   getJsDocDescName,
 } from './common';
 
-function createReactSourceFile(elementFilePath: string, outDir: string) {
-  const elementDetailList = getFileElements(elementFilePath);
+async function createReactSourceFile(elementFilePath: string, outDir: string) {
+  const elementDetailList = await getFileElements(elementFilePath);
   return Object.fromEntries(
     elementDetailList.map(({ name: tag, constructorName, properties, methods }) => {
       const componentName = getComponentName(tag);
@@ -80,10 +80,13 @@ function createReactSourceFile(elementFilePath: string, outDir: string) {
   );
 }
 
-export function compileReact(elementsDir: string, outDir: string): void {
+export async function compileReact(elementsDir: string, outDir: string) {
   const fileSystem: Record<string, string> = {};
-  getElementPathList(elementsDir).forEach((elementFilePath) => {
-    Object.assign(fileSystem, createReactSourceFile(elementFilePath, outDir));
-  });
+
+  const processFile = async (elementFilePath: string) => {
+    Object.assign(fileSystem, await createReactSourceFile(elementFilePath, outDir));
+  };
+
+  await Promise.all(getElementPathList(elementsDir).map(processFile));
   compile(outDir, fileSystem);
 }
diff --git a/packages/gem-port/src/svelte.ts b/packages/gem-port/src/svelte.ts
index 22a8199a..24e4d31c 100644
--- a/packages/gem-port/src/svelte.ts
+++ b/packages/gem-port/src/svelte.ts
@@ -9,10 +9,11 @@ import {
   getRelativePath,
 } from './common';
 
-export function compileSvelte(elementsDir: string, outDir: string, ns = ''): void {
+export async function compileSvelte(elementsDir: string, outDir: string, ns = '') {
   const fileSystem: Record<string, string> = {};
-  getElementPathList(elementsDir).forEach((elementFilePath) => {
-    const elementDetailList = getFileElements(elementFilePath);
+
+  const processFile = async (elementFilePath: string) => {
+    const elementDetailList = await getFileElements(elementFilePath);
     Object.assign(
       fileSystem,
       Object.fromEntries(
@@ -53,6 +54,8 @@ export function compileSvelte(elementsDir: string, outDir: string, ns = ''): voi
         }),
       ),
     );
-  });
+  };
+
+  await Promise.all(getElementPathList(elementsDir).map(processFile));
   compile(outDir, fileSystem);
 }
diff --git a/packages/gem-port/src/vue.ts b/packages/gem-port/src/vue.ts
index def26635..d611275b 100644
--- a/packages/gem-port/src/vue.ts
+++ b/packages/gem-port/src/vue.ts
@@ -27,10 +27,12 @@ declare module '@vue/runtime-dom' {
 }
  */
 
-export function generateVue(elementsDir: string, outDir: string): void {
+export async function generateVue(elementsDir: string, outDir: string) {
   mkdirSync(outDir, { recursive: true });
-  getElementPathList(elementsDir).forEach((elementFilePath) => {
-    getFileElements(elementFilePath).forEach(({ name: tag, properties, constructorName, methods, events }) => {
+
+  const processFile = async (elementFilePath: string) => {
+    const elements = await getFileElements(elementFilePath);
+    elements.forEach(({ name: tag, properties, constructorName, methods, events }) => {
       const componentName = getComponentName(tag);
       const componentMethodsName = `${componentName}Methods`;
       const relativePath = getRelativePath(elementFilePath, outDir);
@@ -115,5 +117,7 @@ export function generateVue(elementsDir: string, outDir: string): void {
       `,
       );
     });
-  });
+  };
+
+  await Promise.all(getElementPathList(elementsDir).map(processFile));
 }