A mobile device includes a device body and a wireless earphone. A back of the device body has an accommodating recess. The device body includes a first processing unit, a first wireless communication unit and a first electrical connector. The first electrical connector is disposed in the accommodating recess. The wireless earphone includes a second processing unit, a second wireless communication unit and a second electrical connector. The wireless earphone is configured to be detachably accommodated in the accommodating recess of the device body. When the wireless earphone is detached from the accommodating recess, the first electrical connector and the second electrical connector are separated from each other, the first processing unit switches on the first wireless communication unit, and the second processing unit switches on the second wireless communication unit, such that the first wireless communication unit and the second wireless communication unit are paired with each other.