After being crushed, the feed stock is carried to the superfine ball mill with a conveyer. The milling balls in the ball mill will impact and grind the feedstock by the energy of the rotating ball mill. The crushed feedstock is carried to the self-diffluent micro-powder classifier through a discharging champer, and completely mixed with air forming a fluid that is classified into coarse and fine powders under the forces of centrifugal classifying blades and the draught of air. The qualified fine powders are collected with a cyclone collector and bag collector. The coarse powders are sent to be recrushed in the ball mill through the lower part of the classifier.