The invention provides a robot for spiral steel pipe welding. The robot for spiral steel pipe welding comprises a welding machine rack, a steel plate bending device, a welding device, a traction device and a supporting device, wherein the welding machine rack is an integral frame of the robot for spiral steel pipe welding, the other devices are all mounted on the welding machine rack, the steel plate bending device machines plate steel plates into spiral steel plates, the welding device is used for welding spiral steel pipe welding seams, the traction device pulls welded steel pipes forward, the traction device provides rotary power for the steel pipes at the same time, and the supporting device plays a role in supporting on the steel pipes with different pipe diameters. The robot for spiral steel pipe welding can weld the spiral steel pipes with different pipe diameters.