人家的官方文档上步骤都有了，按照步骤走就行

安装composer 不作赘述

附一个文档链接：

安装 · ThinkPHP5.1完全开发手册 · 看云

主要说一个自己踩过的坑吧

composer create-project topthink/think=5.1.* tp5

在输入这个命令以后提示 

[Composer\Downloader\TransportException]
The "http://packagist.org/packages.json" file could not be downloaded: failed to open stream: HTTP request failed!

或者

[Composer\Downloader\TransportException]
The "http://packagist.org/packages.json" file could not be downloaded: failed to open stream: HTTP request failed!

只需要将镜像换成阿里的即可

（文档上的说法）

#更改composer镜像源为国内地址
composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/

The "https://repo.packagist.org/p/laravel/laravel.json" file could not be downloaded: failed to open_one312的博客-CSDN博客


第二个坑：

更新完镜像以后，又报

Warning from https://mirrors.aliyun.com/composer: Support for Composer 1 is deprecated and some packages will not be available. You should upgrade to Composer 2. See https://blog.packagist.com/deprecating-composer-1-support/

                                                                                                                        
  [Composer\Downloader\TransportException]                                                                              
  The "https://mirrors.aliyun.com/composer/p/provider-2017%248b8b2c1627e2216d9b910bf3d8218b05804048e6ee6c09746f82e0b39532964a.json" file could not be downloaded (HTTP/1.1 404 Not Found)

此时只需要将composer升级即可

composer 报错 The “https://mirrors.aliyun.com/composer/p....json“ file could not be downloaded (HTTP/1_玻璃人小高的博客-CSDN博客

                           

执行完成以后，项目文件夹里会有一个tp5的文件

此时只需要                                                                                           

测试运行即可