At present, the traditional liquid spraying and manual spraying methods have many problems, such as great paint waste, serious environmental pollution, difficult cleaning, low production efficiency, large color difference of products, unstable quality and so on. Electrostatic painting can solve these problems. Its principle is the same as electrostatic dust removal, and it is a new technology for painting by using electrostatic field formed by high voltage. Compared with manual painting, it has the advantages of high efficiency, less waste, good quality and being beneficial to workers' health. The picture shows the schematic diagram of the electrostatic spray painting device of the rotating cup. Paint enters the high-speed rotating metal cup B through the paint delivery pipe A, and the paint sprayed from the spray cup is atomized due to the high-speed rotation of the spray cup. Due to the negative high voltage (60- 120 kV) connected to the spray cup, the paint mist particles are negatively charged, which repel each other and disperse evenly. At the same time, under the action of electric field force, they fly to the workpiece C connected with positive high voltage, and are adsorbed on the working surface to form a bright and firm paint layer. Electrostatic spray painting will not pollute the air because of its small electric field force range. At present, electrostatic spraying has been widely used in the processing of mechanical parts, train carriages and so on.