Electrostatic spray gun is the basic product of modern industrial spraying equipment. In the coating process line, electrostatic spray gun is the main body of the most core equipment for surface treatment. By using low pressure and high atomization device and generating electrostatic electric field force through electrostatic generator, the coating can be sprayed to the surface of the coating efficiently and quickly, so that the coating can achieve perfect surface treatment. Therefore, the electrostatic spray gun takes the grounded coating as the positive electrode and the coating atomization device as the negative electrode. And the coating atomization device with high negative voltage, in the diode made of electrical boundary, so that the atomized coating particles with negative charge, so that the coating is effectively absorbed on the surface of the opposite electrode method is called electrostatic coating.