一、vite.config.js 重点代码：

（完整代码在下面）

AutoImport({
 resolvers: [
    ElementPlusResolver({
      importStyle: 'sass'
    })
  ],
}),
Components({
  resolvers: [
    ElementPlusResolver({
      // 自动引入修改主题色添加这一行，使用预处理样式
      importStyle: "sass",
    }),
  ],
}),

css: {
  preprocessorOptions: {
     scss: {
       additionalData: `@use "@/assets/styles/theme.scss" as *;`

     }
   },
}

二、main.js不要引入theme

// import './assets/styles/theme.scss';

三、theme.scss中最后一行要去掉

@forward 'element-plus/theme-chalk/src/common/var.scss' with (
  $colors: (
    'white': #ffffff,
    'black': #000000,
    'primary': (
      // 'base': #409eff,
      'base': #e6a23c,
    ),
    'success': (
      'base': #67c23a,
    ),
    'warning': (
      'base': #e6a23c,
    ),
    'danger': (
      'base': #f56c6c,
    ),
    'error': (
      'base': #f56c6c,
    ),
    'info': (
      'base': #909399,
    ),
  ),
);

// @use "element-plus/theme-chalk/src/index.scss" as *;

附

vite.config.js
完整代码

import { defineConfig } from 'vite'
import vue from '@vitejs/plugin-vue'
import path from 'path'
import compressPlugin from 'vite-plugin-compression'
// element-plus 按需导入
import AutoImport from 'unplugin-auto-import/vite'
import Components from 'unplugin-vue-components/vite'
import { ElementPlusResolver } from 'unplugin-vue-components/resolvers'


// https://vitejs.dev/config/
export default defineConfig({
  base: '/', // 设置打包路径，默认为 / 
  plugins: [
    vue(),
    
    compressPlugin({
      threshold: 3072, //3KB 仅压缩文件大小大于此阈值的文件
      deleteOriginFile: true, // 是否删除原始文件
      verbose: false	// boolean	true	是否在控制台中输出压缩结果
    }),
    AutoImport({
      resolvers: [
        ElementPlusResolver({
          importStyle: 'sass'
        })
      ],
    }),
    Components({
      resolvers: [
        ElementPlusResolver({
          // 自动引入修改主题色添加这一行，使用预处理样式
          importStyle: "sass",
        }),
      ],
    }),
  ],
  resolve: {
    alias: {
      '@': path.resolve(__dirname, './src')
    }
  },
  server: {
    port: 6699,
    host: '0.0.0.0',
    proxy: {
      '/api': {
        target: 'http://localhost:8091', //目标url
        changeOrigin: true, //支持跨域
        rewrite: (path) => path.replace(/^\/api/, ""), 
          //重写路径,替换/api
      }
    }
  },
  css: {
    preprocessorOptions: {
      scss: {
        additionalData: `@use "@/assets/styles/theme.scss" as *;`

      }
    },
  }

})