The present invention discloses an interface sharing apparatus and method, and a mobile communications terminal. The apparatus includes a control unit, a video processing unit, a switch unit, a detection control unit and a multiplexing interface. The detection control unit is configured to detect a first voltage from the multiplexing interface, and to compare the first voltage with a preset voltage value. If the first voltage is greater than zero and less than or equal to the preset voltage value, the detection control unit controls the switch unit, so that the video processing unit is connected to the multiplexing interface by using the switch unit. If the first voltage is equal to zero or greater than the preset voltage value, the detection control unit controls the switch unit, so that the control unit is connected to the multiplexing interface by using the switch unit.