Disclosed is a superfine powder electrostatic grading device, comprising a feeding part of the powder, an electrostatic dispersion part, an grading part, a product collector, a high voltage electrostatic power supply and an electrostatic power supply. The feeding part includes a charging barrel which is equipped with a vibrating motor and a switch. The electrostatic dispersion part is a barrel-shape structure with insulating material, and the electrodes used to electrify the powder are evenly distributed on the wall of the barrel; the charging barrel is inserted in the dispersion barrel. The circumambience of the dispersion barrel is connected with electrodes; the bottom of the dispersion barrel is shrunk; the electrostatic grading part is composed of a square grading chamber and two opposite electrostatic electrodes, the bottom of the dispersion barrel is inserted in the square grading chamber; the electrostatic electrodes are wire meshes or metal sheets on the two opposite whole surfaces of the grading chamber; the product collector is arranged on the bottom of the grading part. The invention has the advantages that the invention is suitable for the grading of the superfine powder with high grading rate, simple structure, convenient and closed operation; and has no environmental pollution.