1、到ruby官网下载ruby，并安装
2、下载DevKit，并解压ruby安装目录的任意目录下，eg.kit目录下分别运行
ruby dk.rb init ruby dk.rb install
3、安装所需要的gem包
1）安装之前会遇到的问题
ERROR: While executing gem ... (Gem::RemoteFetcher::FetchError)
SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (https://api.rubygem
s.org/specs.4.8.gz) 解决办法，参考网站
This assumes your have already installed the Rails Installer for Windows.
Download the ruby script to your Desktop folder fromhttps://gist.github.com/raw/867550/win_fetch_cacerts.rb. Then in your command prompt, execute the ruby script:
ruby "%USERPROFILE%\Desktop\win_fetch_cacerts.rb"
Now make ruby aware of your certificate authority bundle by setting SSL_CERT_FILE. To set this in your current command prompt session, type:
set SSL_CERT_FILE=C:\RailsInstaller\cacert.pem
gem update --system gem install rspec --no-ri --no-rdoc gem install win32console --no-ri --no-rdoc gem install watir-webdriver --no-ri --no-rdoc gem install cucumber --no-ri --no-rdoc
cucumber --version
原文：http://my.oschina.net/liyonglee/blog/351500