The utility model discloses a cylinder face of weld is to meeting sb. At airport belongs to welding auxiliary assembly field for cylindrical structures's butt joint, it includes the frame, a plurality of last backing roll, lower supporting roller that set up are in pairs installed respectively to the both sides of frame, install driving roller, help roll between the last backing roll that sets up in pairs in frame both sides, the lower supporting roller, install the transmission shaft in the driving roller, the transmission shaft mentions the chain through the transmission and is connected with power unit. In view of above -mentioned technical scheme, the utility model discloses can realize reducing the butt joint degree of difficulty of large -scale barrel welded structure before the welding, improve the welding quality of labor efficiency and product, reduce the purpose of the risk of emergence incident.