The shock absorber is used to suppress the shock and the impact from the road surface when the spring rebounds after shock absorption. Widely used in automobiles, in order to accelerate the attenuation of the vibration of the frame and the body to improve the ride comfort of the car. When passing through an uneven road, although the shock-absorbing spring can filter the vibration of the road, the spring itself will have a reciprocating motion, and the shock absorber is used to suppress the spring jump.