The present invention discloses a distributed type electrified welding system for an aluminium electrolytic tank cathode steel bar. The system comprises an aluminium electrolytic tank shunting apparatus (3). The aluminium electrolytic tank shunting apparatus (3) is connected between an overhauling tank anode large bus bar and a downstream tank column bus bar, and forms an electrical connection with a voltage probe (1), a temperature sensor (2) and an industrial personal computer (4). With the present invention, the tank bottom short-circuit current of the overhauling electrolytic tank can be shunted or drained; at the same time, during the shunting process and the draining process, the current of the draining apparatus is uninterruptedly monitored, the control and the abnormal alarm are provided for the technical process, such that the efficiency of the electrolytic production is greatly improved, and the welding quality of the cathode steel bar and the cathode soft belt is ensured.