1，命令行修改
gem sources --add https://gems.ruby-china.com/ --remove https://rubygems.org/
# gem sources --add https://gems.ruby-china.com/
# gem sources --remove https://rubygems.org/
gem sources --clear-all
gem sources --update
# test source
gem sources -l
2，手动修改
Gemfile
# default
source "https://rubygems.org"
# china
source "https://gems.ruby-china.com/"