Battery box welding tool

The utility model relates to the technical field of frequency converters, in particular to a battery box welding tool which comprises a bottom plate, a support plate used for abutting against the rear wall of a battery box is fixedly connected to the bottom plate, a pneumatic cylinder is fixedly connected to the support plate, and a cylinder body of the pneumatic cylinder is fixedly installed on the side, abutting against the rear wall of the battery box, of the support plate; a piston rod of the pneumatic cylinder extends out from the upper end of the bracket plate, and is provided with a clamping plate for abutting against one side, back to the bracket plate, of the rear wall of the battery box. The rear wall is fixed on the bracket plate, and then the rear wall is fixed by utilizing the matching between the clamping plate and the pneumatic cylinder, so that the rear wall is connected to the bracket plate, and the rear wall and the bottom wall are welded and fixed, so that a worker does not need to support