You can install the default Ubuntu desktop by executing the following:

sudo apt-get install ubuntu-desktop

There are many desktop alternatives which you may install and use, like:

• Gnome 3 installation: sudo apt-get install gnome-shell

转自： http://askubuntu.com/questions/53822/how-do-you-run-ubuntu-server-with-a-gui

ubuntu14.04 server安装gnome-desktop