如果你安装了Homebrew，你可以这样做。

# check the zsh info
brew info zsh

# install zsh
brew install --without-etcdir zsh

# add shell path
sudo vim /etc/shells

# add the following line into the very end of the file(/etc/shells)
/usr/local/bin/zsh

# change default shell
chsh -s /usr/local/bin/zsh

希望有帮助，谢谢。