The utility model relates to an auxiliary welding fixing device which overcomes the defect that an existing welding clamp has difficulties in locating two cross parts of a certain angle. The auxiliary welding device can adjust relative angles of parts and fix the parts at will and comprises a disk-shaped base plate. A fixed clamping device and a movable clamping device are connected to the base plate, the fixed clamping device comprises a U-shaped fixed frame fixedly connected with the base plate, and an abutting screw is arranged on one side of the U-shaped fixed frame. The movable clamping device comprises a bottom frame, wherein a flat plate structure is arranged at one end of the bottom frame. A pin hole is formed in a flat plate, the pin hole is matched with a pin shaft arranged in the center of the base plate, a U-shaped structure is arranged at the other end of the bottom frame, the two sides of the U-shaped structure are bent upwards, downward barbs are arranged at the ends of the U-shaped structure, abutting screws are at least arranged on one lateral side of the U-shaped structure, and abutting screws are arranged at the lower lateral edges of the barbs. The auxiliary welding fixing device can effectively weld and locate two or a plurality of cross parts of certain angles and has the advantages of improving effects and guaranteeing quality.