The invention discloses a special crusher for waste casting iron pieces, comprising a rack, a fixed jaw plate, a swinging shaft, a movable jaw plate, a hydraulic cylinder, semi-cylindrical conical teeth I and semi-cylindrical conical teeth II, wherein three rows of semi-cylindrical conical teeth I are arranged in parallel from top to bottom on the fixed jaw plate; and a gap L with same size is arranged between every two rows of semi-cylindrical conical teeth I. Four rows of same semi-cylindrical conical teeth II are arranged in parallel from top to bottom on the movable jaw plate; and a gap with same size is arranged between every two rows of semi-cylindrical conical teeth II. When the movable jaw plate and the fixed jaw plate of the crusher are meshed, the four rows of semi-cylindrical conical teeth II on the movable jaw plate and the three rows of semi-cylindrical conical teeth I on the fixed jaw plate are arranged horizontally at intervals. The invention provides the special crusher for the waste casting iron pieces, which has the functions of extrusion and shearing. According to the crusher, the branch-shaped waste casting iron pieces formed by casting heads and runners and the like can be quickly and effectively extruded and sheared into small casting iron blocks; and since the small casting iron blocks are arranged closely in an electric induction furnace, the occupied space is small, the melting can be quick and the power consumption is lower.