方法一 安装器安装：缺点不能安装指定版本

composer global require "laravel/lumen-installer"

lumen new blog

composer global require "laravel/laravel-installer"

laravel new blog

方法二 ：安装指定版本

composer create-project --prefer-dist laravel/lumen lumen55 '5.6.*'

composer create-project --prefer-dist laravel/laravel blog 5.6.*

如果报错插件

composer create-project --prefer-dist --no-plugins  laravel/lumen lumen5 '5.6.*'