Electroplating is an electrochemical process that occurs at the interface between metal and electrolyte. Obviously, to ensure the quality of electroplating products, in the field production must strictly ensure that the electrolyte and the surface of the plating always maintain good contact, if the contact between them is poor, the electrochemical reaction can not be carried out. Due to improper pre-plating process or maintenance operation, the oil, rust and oxide attached to the surface of the metal plating hinder the direct contact between the electrolyte and the plating. They are sandwiched between the coatings, which will cause poor product quality, so the cleanliness of the surface of the metal plating and the quality of the surface condition are the primary conditions for obtaining high-quality coatings. For a long time, most of the quality accidents in production are not problems with the plating process itself, but mostly due to improper treatment before plating. Therefore, the flat degree, binding force, corrosion resistance and other properties of the coating are closely related to the pre-plating treatment.