diff --git a/electron.vite.config.ts b/electron.vite.config.ts
index 9b22ffc33b..fa4b234a54 100644
--- a/electron.vite.config.ts
+++ b/electron.vite.config.ts
@@ -68,12 +68,16 @@ export default defineConfig({
       }
     },
     optimizeDeps: {
-      exclude: ['pyodide']
+      exclude: ['pyodide'],
+      esbuildOptions: {
+        target: 'esnext' // for dev
+      }
     },
     worker: {
       format: 'es'
     },
     build: {
+      target: 'esnext', // for build
       rollupOptions: {
         input: {
           index: resolve(__dirname, 'src/renderer/index.html'),
diff --git a/package.json b/package.json
index 3ee50ee69a..72e1f64856 100644
--- a/package.json
+++ b/package.json
@@ -168,6 +168,7 @@
     "husky": "^9.1.7",
     "i18next": "^23.11.5",
     "jest-styled-components": "^7.2.0",
+    "linguist-languages": "^8.0.0",
     "lint-staged": "^15.5.0",
     "lodash": "^4.17.21",
     "lru-cache": "^11.1.0",
diff --git a/src/renderer/src/components/CodeBlockView/index.tsx b/src/renderer/src/components/CodeBlockView/index.tsx
index 944e6f66e3..811b8665cc 100644
--- a/src/renderer/src/components/CodeBlockView/index.tsx
+++ b/src/renderer/src/components/CodeBlockView/index.tsx
@@ -4,7 +4,7 @@ import { CodeTool, CodeToolbar, TOOL_SPECS, useCodeTool } from '@renderer/compon
 import { useSettings } from '@renderer/hooks/useSettings'
 import { pyodideService } from '@renderer/services/PyodideService'
 import { extractTitle } from '@renderer/utils/formats'
-import { isValidPlantUML } from '@renderer/utils/markdown'
+import { getExtensionByLanguage, isValidPlantUML } from '@renderer/utils/markdown'
 import dayjs from 'dayjs'
 import { CirclePlay, CodeXml, Copy, Download, Eye, Square, SquarePen, SquareSplitHorizontal } from 'lucide-react'
 import React, { memo, useCallback, useEffect, useMemo, useState } from 'react'
@@ -67,23 +67,21 @@ const CodeBlockView: React.FC<Props> = ({ children, language, onSave }) => {
     window.message.success({ content: t('code_block.copy.success'), key: 'copy-code' })
   }, [children, t])
 
-  const handleDownloadSource = useCallback(() => {
+  const handleDownloadSource = useCallback(async () => {
     let fileName = ''
 
-    // 尝试提取标题
+    // 尝试提取 HTML 标题
     if (language === 'html' && children.includes('</html>')) {
-      const title = extractTitle(children)
-      if (title) {
-        fileName = `${title}.html`
-      }
+      fileName = extractTitle(children) || ''
     }
 
     // 默认使用日期格式命名
     if (!fileName) {
-      fileName = `${dayjs().format('YYYYMMDDHHmm')}.${language}`
+      fileName = `${dayjs().format('YYYYMMDDHHmm')}`
     }
 
-    window.api.file.save(fileName, children)
+    const ext = await getExtensionByLanguage(language)
+    window.api.file.save(`${fileName}${ext}`, children)
   }, [children, language])
 
   const handleRunScript = useCallback(() => {
diff --git a/src/renderer/src/utils/__tests__/markdown.test.ts b/src/renderer/src/utils/__tests__/markdown.test.ts
index cbde058d24..7b82816f17 100644
--- a/src/renderer/src/utils/__tests__/markdown.test.ts
+++ b/src/renderer/src/utils/__tests__/markdown.test.ts
@@ -7,6 +7,7 @@ import {
   convertMathFormula,
   findCitationInChildren,
   getCodeBlockId,
+  getExtensionByLanguage,
   markdownToPlainText,
   removeTrailingDoubleSpaces,
   updateCodeBlock
@@ -143,6 +144,67 @@ describe('markdown', () => {
     })
   })
 
+  describe('getExtensionByLanguage', () => {
+    // 批量测试语言名称到扩展名的映射
+    const testLanguageExtensions = async (testCases: Record<string, string>) => {
+      for (const [language, expectedExtension] of Object.entries(testCases)) {
+        const result = await getExtensionByLanguage(language)
+        expect(result).toBe(expectedExtension)
+      }
+    }
+
+    it('should return extension for exact language name match', async () => {
+      await testLanguageExtensions({
+        '4D': '.4dm',
+        'C#': '.cs',
+        JavaScript: '.js',
+        TypeScript: '.ts',
+        'Objective-C++': '.mm',
+        Python: '.py',
+        SVG: '.svg',
+        'Visual Basic .NET': '.vb'
+      })
+    })
+
+    it('should return extension for case-insensitive language name match', async () => {
+      await testLanguageExtensions({
+        '4d': '.4dm',
+        'c#': '.cs',
+        javascript: '.js',
+        typescript: '.ts',
+        'objective-c++': '.mm',
+        python: '.py',
+        svg: '.svg',
+        'visual basic .net': '.vb'
+      })
+    })
+
+    it('should return extension for language aliases', async () => {
+      await testLanguageExtensions({
+        js: '.js',
+        node: '.js',
+        'obj-c++': '.mm',
+        'objc++': '.mm',
+        'objectivec++': '.mm',
+        py: '.py',
+        'visual basic': '.vb'
+      })
+    })
+
+    it('should return fallback extension for unknown languages', async () => {
+      await testLanguageExtensions({
+        'unknown-language': '.unknown-language',
+        custom: '.custom'
+      })
+    })
+
+    it('should handle empty string input', async () => {
+      await testLanguageExtensions({
+        '': '.'
+      })
+    })
+  })
+
   describe('getCodeBlockId', () => {
     it('should generate ID from position information', () => {
       // 从位置信息生成ID
diff --git a/src/renderer/src/utils/markdown.ts b/src/renderer/src/utils/markdown.ts
index e4881ed062..3c409d39b4 100644
--- a/src/renderer/src/utils/markdown.ts
+++ b/src/renderer/src/utils/markdown.ts
@@ -54,6 +54,60 @@ export function removeTrailingDoubleSpaces(markdown: string): string {
   return markdown.replace(/ {2}$/gm, '')
 }
 
+const predefinedExtensionMap: Record<string, string> = {
+  html: '.html',
+  javascript: '.js',
+  typescript: '.ts',
+  python: '.py',
+  json: '.json',
+  markdown: '.md',
+  text: '.txt'
+}
+
+/**
+ * 根据语言名称获取文件扩展名
+ * - 先精确匹配，再忽略大小写，最后匹配别名
+ * - 返回第一个扩展名
+ * @param language 语言名称
+ * @returns 文件扩展名
+ */
+export async function getExtensionByLanguage(language: string): Promise<string> {
+  const lowerLanguage = language.toLowerCase()
+
+  // 常用的扩展名
+  const predefined = predefinedExtensionMap[lowerLanguage]
+  if (predefined) {
+    return predefined
+  }
+
+  const languages = await import('linguist-languages')
+
+  // 精确匹配语言名称
+  const directMatch = languages[language as keyof typeof languages] as any
+  if (directMatch?.extensions?.[0]) {
+    return directMatch.extensions[0]
+  }
+
+  // 大小写不敏感的语言名称匹配
+  for (const [langName, data] of Object.entries(languages)) {
+    const languageData = data as any
+    if (langName.toLowerCase() === lowerLanguage && languageData.extensions?.[0]) {
+      return languageData.extensions[0]
+    }
+  }
+
+  // 通过别名匹配
+  for (const [, data] of Object.entries(languages)) {
+    const languageData = data as any
+    if (languageData.aliases?.includes(lowerLanguage)) {
+      return languageData.extensions?.[0] || `.${language}`
+    }
+  }
+
+  // 回退到语言名称
+  return `.${language}`
+}
+
 /**
  * 根据代码块节点的起始位置生成 ID
  * @param start 代码块节点的起始位置
diff --git a/yarn.lock b/yarn.lock
index a0daa3b3ce..688f7f8f5d 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -5688,6 +5688,7 @@ __metadata:
     i18next: "npm:^23.11.5"
     jest-styled-components: "npm:^7.2.0"
     jsdom: "npm:26.1.0"
+    linguist-languages: "npm:^8.0.0"
     lint-staged: "npm:^15.5.0"
     lodash: "npm:^4.17.21"
     lru-cache: "npm:^11.1.0"
@@ -11874,6 +11875,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"linguist-languages@npm:^8.0.0":
+  version: 8.0.0
+  resolution: "linguist-languages@npm:8.0.0"
+  checksum: 10c0/eaae46254247b9aa5b287ac98e062e7fe859314328ce305e34e152bc7bb172d69633999320cb47dc2a710388179712a76bb1ddd6e39e249af2684a4f0a66256c
+  languageName: node
+  linkType: hard
+
 "linkify-it@npm:^5.0.0":
   version: 5.0.0
   resolution: "linkify-it@npm:5.0.0"