Electrostatic powder spraying machine works based on the principle of electrostatic adsorption. When the powder coating is ejected from the spray gun, the powder particles are negatively charged through the action of the high voltage electrostatic field. And the coated workpiece is grounded, forming a positive potential difference. Under the traction of the electric field force, the negatively charged powder particles are quickly and evenly adsorbed to the surface of the workpiece, forming a flat and dense coating. Subsequently, after the heating treatment of the curing furnace, the powder coating melts, flows flat and solidifies, tightly combined with the surface of the workpiece.