Electrophoretic coating is to put the workpiece and the corresponding electrode into a water-soluble coating. After connecting the power supply, rely on the physical and chemical action generated by the electric field to make the resin and pigment and filler in the coating uniform on the surface of the electrode to be coated. A coating method by precipitation to form a water-insoluble paint film. Electrophoretic coating is a very complicated electrochemical reaction process, which includes at least four processes: electrophoresis, electrodeposition, electroosmosis, and electrolysis. Electrophoretic coating can be divided into anodic electrophoresis (workpiece is anode, coating is anionic) and cathodic electrophoresis (workpiece is cathode, coating is cationic) according to deposition performance; according to power supply, it can be divided into DC electrophoresis and AC electrophoresis; There are constant voltage and constant current methods. The anode electrophoresis of the constant voltage method of DC power supply is widely used in industry.