This seam tracking welding is a universal automatic welding equipment for butt longitudinal seam welding. It can be used for high-quality welding of materials such as carbon steel, low alloy steel, stainless steel, aluminum and its alloys, and can select argon arc welding (with or without wire), melting gas shielded welding (CO2/MIG/MAG), plasma welding, submerged arc welding and other welding power sources to form a set of longitudinal seam automatic welding system.