Shortly after Xiaomi and China Mobile released the Mi Notebook Air in China, a website got their hands on the 12.5 inch version and let us take a look inside. As you can see, there is no SIM card slot on the machine.
http://www.notebookcheck.net/Xiaomi-Mi-Notebook-Air-4G-Take-a-peek-inside-and-check-out-the-LTE-module.188942.0.html