The embodiments of the present disclosure provide a plug, an interface device and an identification method thereof. The plug includes at least one insulating pin row including a plurality of insulating pins, a conductive pin which is stretchable and retractable along an axis direction is provided on at least one side of a central line of each of the at least one insulating pin row, and the conductive pin is arranged between two adjacent insulating pins of the plurality of insulating pins.