Welding assist device, welding system, and welding method

The invention discloses a welding auxiliary device, a welding system and a welding method.The welding auxiliary device comprises a mounting frame, a welding auxiliary device and a welding auxiliary device, the pole positioning piece is arranged on the mounting frame; the bearing mechanism is arranged on the mounting frame, the bearing mechanism comprises a carrier which is arranged opposite to the pole positioning piece, the carrier is provided with a bearing surface which is arranged opposite to the pole positioning piece, a gas channel is arranged in the carrier, and a gas outlet of the gas channel penetrates through the bearing surface; the inflating mechanism is used for inflating gas into the gas channel; wherein the bearing surface is used for placing a battery semi-finished product, so that a central hole of a battery cell of the battery semi-finished product is opposite to a gas outlet of the gas channel; and the pole positioning piece can be pressed on the pole of the battery semi-finished product. B