Rectangular pipe welding positioning tool

The utility model discloses a rectangular pipe welding positioning tool which comprises an inverted-U-shaped clamping base formed by connecting a top plate and two side plates, at least one of the two side plates is provided with a positioning assembly, the positioning assembly is arranged on the outer side of the side plate, the positioning assembly comprises a transverse plate and a vertical plate which are perpendicular to each other, and the transverse plate and the vertical plate are perpendicular to each other. The transverse plate and the vertical plate are both perpendicular to the side plate and fixedly connected with the side plate, the transverse plate and the vertical plate form a positioning space extending along the inner side face of the side plate on one side of the inverted-U-shaped clamping seat, during use, the inverted-U-shaped clamping seat is arranged on a rectangular pipe in a buckled mode, the bottom wall and the side wall of a to-be-welded rectangular pipe perpendicular to the rectang