The present invention is to provide a method of switching communication modules of a communication device, wherein said communication device comprises a control module and a built-in communication module and has a connecting port on a surface thereof, and the control module respectively connects to the connecting port and the built-in communication module. When the connecting port connects to an external communication module, the control module is able to activate both the external communication module and the built-in communication module, or alternatively one of the external communication module or the built-in communication module.