It is the welding asistance equipment, which machine head is equipped on the top of the boom, which can be elevated and retracted horizontal free by the boom, also rotated by ± 180o; This machine can be used together with welding rotator, welding positioner and achieves the tank longitudinal and circle seam welding. According to the requirement, which can be adopted welding seam tracing and monitoring, welding flux recovery and feeding device. It has the structures of fixed type, fixed with rotation and moveable with rotation type.