The invention provides an automatic updating mechanism for a contact interface of lithiation of positive electrode powder. The automatic updating mechanism is placed in a constant-gaseous-environment catalyst case and comprises a lithiation disc, supports, a transmission base plate, a crossbeam, springs, mechanical lithiation teeth, fixing pins, stop nuts and a lithiation crossbeam, wherein the tail ends of the mechanical lithiation teeth are sleeved by the springs, then the mechanical lithiation teeth are inserted into corresponding holes in the crossbeam and then the stop nuts are screwed on the tail ends of the mechanical lithiation teeth; positioning pins protruding from the bottom of the lithiation disc are inserted into corresponding holes in the transmission base plate; and the lithiation crossbeam is placed on the support and the fixing pins are inserted. Preferably, after the tail ends of the mechanical lithiation teeth pass through the crossbeam, the stop nuts are connected with the tail ends of the mechanical lithiation teeth through threads. The mechanical lithiation teeth and the crossbeam are positioned via the stop nuts, and the stop nuts are pressed to the crossbeam via the pressure of the springs. The lithiation disc and the transmission base plate are positioned via cylindrical pins. Preferably, the lithiation disc and the supports are positioned via pins.