The powder Classifier is operated under negative pressure. The material for grinding is fed from the inlet of the powder separator. The vortex flow entering the primary air outlet is separated by the scattering disc and dispersed by the suspension and dispersion mechanism. After that, a coarse subdivision level is realized in the horizontal vortex field formed by the airflow entering through the secondary tuyere in the classification zone, and the fine powder enters the cage and is drawn from the fine powder outlet by the negative pressure air into the subsequent cyclone collector, and is collected by the collector. Finished product, the coarse powder falls into the cone and is discharged through the coarse powder outlet and returned to the mill for grinding again.