Automobile body sheet metal parts are mainly produced in batches, and the forming process is usually completed on mechanical equipment. Manual operation is mainly auxiliary processing, single-piece processing or repair. Manual processes commonly used in sheet metal production include bending, edge sealing, edge standing, edge drawing, edge curling, seam biting and correction. In addition, the permanent connection between sheet metal parts can be realized by welding and willow connection. In the process of automobile use, various kinds of damage often occur to body sheet metal parts, including wear, corrosion, fracture, uneven or torn metal plates, wrinkling, bending and twisting. These damages may be caused by wear, corrosion, cracks and other reasons. In the process of vehicle operation, it may also be caused by accidental collision and unreasonable design. Therefore, when repairing sheet metal parts, it is necessary to analyze different damage situations and adopt different repair methods and sequences to achieve satisfactory results. Repairing wrinkles and lumps requires different methods. For convex surface, it can be repaired by hammering or jacking, and for slight concave-convex damage, it can be placed with pad iron, hammered and finally slightly trimmed. In the process of repairing, it is necessary to observe the overall smoothness of the board surface in order to achieve the effect of repairing. For concave surface, direct jacking or drilling and stretching can be adopted. For fold damage, concave-convex damage repair method can also be used to repair it. For the repair of bending and distortion, it is necessary to correct it by supporting, and the direction of supporting force should be opposite to that of deformation force. If the frame is deformed, it can be repaired by jacking device. For the tearing caused by external impact extrusion, it is necessary to grind the torn part flat first, and then weld it to repair the ductile bulge. For the serious problem of "lack of meat", it is necessary to consider repairing or replacing new parts. If it needs to be repaired, it can be dug into a simple geometric shape and filled with the same material and thickness as the original, and it is best to use CO2 gas shielded welding.