A docking device operates in an active mode or a passive mode. The docking device includes a path control module, a processing module and a switch. The processing module is connected to the switch, and the switch is connected between the path control module and the processing module. The path control module is configured to receive a signal from a host device. When the path control module does not receive the signal from the host device, the docking device operates in the active mode, and the processing module is connected to a plurality of function modules through the switch. When the path control module receives the signal from the host device, the docking device operates in the passive mode, and the path control module is connected to the function modules through the switch.