Automotive sheet metal is a processing method of automobile maintenance, also called cold working. To put it bluntly, if the appearance of the car body is damaged and deformed, the sheet metal process is needed. Automobile collision repair has developed from the initial "welding repair" to the secondary manufacturing and assembly of the car body. The repair of vehicles in collision accidents is no longer a simple automotive sheet metal knock, and the quality of repair can not be observed only by naked eyes. Maintenance personnel should not only know the technical parameters and dimensions of the car body, but also master the characteristics of the car body material, the transmission of force characteristics, the deformation trend and stress points of the car body and the production technology of the car body such as welding technology. On the basis of mastering this knowledge, maintenance personnel should also use advanced measuring tools and accurate three-dimensional measurement of the car body to judge the direct and indirect damage and deformation of the car body and the hidden dangers caused by the deformation of the car body, formulate a complete car body repair plan, and then cooperate with correct maintenance technology and accurate three-dimensional data of key points to restore the car body to its original position and restore the damaged car body to the factory state.