When a back cover of a mobile communication device with replaceable cover is replaced, the mobile communication device may perform a corresponding application or enable a special function according to the back cover. The mobile communication device includes a back cover and a body including a processing unit, a storage unit, and a second connection interface. The back cover includes an integrated circuit (IC) element and a first connection interface. The IC element has identification information. The storage unit stores at least an application and a mapping table. The mapping table records the corresponding application of each identification information. When the back cover is assembled to the body, the first connection interface is connected to the second connection interface. The processing unit receives the identification information and looks up the mapping table according the identification information. The processing unit enables the corresponding application according to the mapping table.