The electromotor drives the rotor to rotate at high speed, when the materials are fed into the crushing chamber, they are crushed by impacting, cutting, hitting and grinding from the hammer which is moving with high speed. On the bottom of the rotor, there is sieve plate, the crushed materials with smaller size than the screen size are discharged from the sieve plate, and the coarse particles bigger than the screen size are retain on the sieve plate for further hitting and grinding by the hammer until they are crushed to the required granularity, and then discharged from the sieve plate