The loading conveyor conveys the plastic pallets evenly to the crushing knife box of the double-shaft crusher, and the alloy steel knives pre-crush the plastics, and the crushed materials are sent by the conveying belt conveyor to the single-shaft crusher or pulverizer to be finely crushed in order to meet the demand for transportation or made into plastic granules, and a magnetic separator is installed on the belt conveyor between the two crusher, which is capable of separating out the iron substances contained in the plastics.