打开终端输入下面命令运行：

defaults write com.apple.AppleMultitouchTrackpad Clicking -bool true
sudo defaults write com.apple.driver.AppleBluetoothMultitouch.trackpad Clicking -bool true
 sudo defaults -currentHost write NSGlobalDomain com.apple.mouse.tapBehavior -int 1
 sudo defaults write NSGlobalDomain com.apple.mouse.tapBehavior -int 1

关闭命令：

defaults write com.apple.AppleMultitouchTrackpad Clicking -bool false
sudo defaults write com.apple.driver.AppleBluetoothMultitouch.trackpad Clicking -bool false
 sudo defaults -currentHost write NSGlobalDomain com.apple.mouse.tapBehavior -int 0
 sudo defaults write NSGlobalDomain com.apple.mouse.tapBehavior -int 0

重启就看到效果了。