Throttle ring used in piston type compressor

The utility model relates to a throttle ring used in a piston type compressor. Because the inner wall of the throttle ring is provided with a plurality of grooves, air can generate great pressure drop when flowing through the whole throttle ring. Therefore, the sealing pressure of a following packing gland is reduced, the service life of a piston packing gland and a piston rod is prolonged, and the running rate of a compressor is improved. The center of the throttle ring is a through hole. The utility model is characterized in that the wall surface of the through hole is a groove surface which forms a wave shape along the axial lead of the throttle ring.