In the plating bath with galvanized liquid, after cleaning and special pretreatment of the plated parts as the cathode, the anode is made of coated metal, the poles are respectively connected with the positive and negative polarity of the DC power supply. The zinc plating solution consists of a compound containing a metal coating, a conductive salt, a buffer, a ph regulator and an additive, and other aqueous solutions. After power-on, the metal ions in the galvanized liquid are moved to the cathode to form a coating under the action of potential difference. The anode metal forms metal ions into the galvanized liquid to maintain the concentration of the metal ions being coated. In some cases, such as chromium plating, is the use of lead, lead antimony alloy made of insoluble anode, it only transmits electrons, conduction current effect. The concentration of chromium ions in the electrolyte must be maintained by adding chromium compounds to the plating solution periodically. When galvanizing, the quality of the anode material, the composition of the galvanized liquid, the temperature, the current density, the power-on time, the stirring strength, the impurities, the power waveform and so on will affect the quality of the coating and need to be controlled in time.