The surface treatment of aluminum castings is a process of artificially forming a surface layer on the surface of the matrix material, which is different from the mechanical, physical and chemical properties of the matrix. The purpose of surface treatment is to meet the corrosion resistance, wear resistance, decoration or other special functional requirements of the product. For metal castings, our more commonly used surface treatment methods are mechanical grinding, chemical treatment, surface heat treatment, spraying surface, surface treatment is to clean, clean, deburr, deoil, deoxidize and so on. In the process of processing, transportation and storage, the surface of the workpiece is often covered with oxide scale, rust molding sand, welding slag, dust, oil and other dirt. The deep layer should be firmly attached to the workpiece surface, and the workpiece surface should be cleaned before painting, otherwise, it will not only affect the adhesion and corrosion resistance between the coating and the metal, but also make the base metal continue to corrode even under the protection of the coating, peeling off the coating and affecting the mechanical properties and service life of the workpiece. Therefore, the surface treatment of the workpiece before painting is an important guarantee and measure to obtain a high quality protective layer and prolong the service life of the product.