$ gem sources --remove https://rubygems.org/
$ gem sources -a https://ruby.taobao.org/
$ gem sources -l
*** CURRENT SOURCES ***
https://ruby.taobao.org
# 请确保只有 ruby.taobao.org
$ gem install rails
淘宝RubyGems 镜像
原文：http://my.oschina.net/u/991892/blog/331994
