The rotor disc under the driving of the motor, to drive the hammer in high speed motion, when the material into the crushing chamber, the bulk materials piled up in the machine in the middle of the special central bar, after crushing size larger than required materials with new material along the tangential direction of hammer hit back plate broken again, so that the rough, broken a the last step, to meet the requirements of the material by the grate plate are qualified after unloading the whole.