An audio and video signal transmission interface apparatus includes a left sound channel interface, a right sound channel interface, a multimedia terminal interface, and a ground interface; where a first power supply and a first resistor are connected in series in the multimedia terminal interface; and the apparatus further includes a voltage detecting module, a determining module, a control module, and a second resistor connected in series in the multimedia terminal interface, where a resistance value of the second resistor is greater than an internal resistance value of an audio and video terminal and smaller than an internal resistance value of a microphone terminal in reverse connection; the determining module identifies different types of transmission lines by using a voltage value measured by the voltage detecting module; and the control module is configured to implement adaptation of different transmission lines.