Powder coating is the use of corona discharge to make powder coatings adsorbed on the workpiece. The process is: powder coating gun is connected to the anode. The workpiece grounding (Positive pole), powder coating by powder supply system by compressed air into the gas gun, a high voltage of the high-voltage electrostatic generator in the gun front. Due to the corona discharge, producing a dense charge in its vicinity by powder spout gun, a loop is formed charged coating particles, it is affected by the electrostatic force, rather than being sucked into the opposite polarity with the workpiece up, spray powder increased, the charge accumulation is more also. When reaches a certain thickness, due to electrostatic repulsion, will not continue to adsorption, powder coating so that the workpiece thickness, and then after the heat of the powder melting, leveling and curing, which form a hard coating on the surface of the workpiece.