This machine takes advantages of the gravity of the raw material and the raw material and the centrifugal force generated  by the rotation of the cylinder.Thus makes the raw materials fly along spiral orbit and makes the material being thrown forward and upward.The grains of the materals that are smaller than the mesh will be thrown out under the pressure of centrifugal force ,thus the materials are sieved.This machine is featured with simple structure,jamming no mesh(due to strong centrifugal force and high sieving efficiency.