The shock absorber is the main damping element of an automotive suspension system and plays an important role in smoothness and safety of automobiles. When the automobile runs on different roads, the automobile frame (or bearing chassis) and the driving axle (or wheels) do reciprocating motion, and the function of the automobile suspension is to transmit vertical reactive force (bearing force), longitudinal reactive force (tractive force and braking force) and lateral reactive force of road surface against wheels and torques caused by the reactive force to the automobile frame (or bearing chassis) so as to guarantee normal running of the automobile. The working mechanism of the suspension shock absorber is that when the automobile frame and the driving axle do reciprocating motion, the piston of the shock absorber also does reciprocating motion in the cylinder, oil in the shell of the shock absorber repeatedly flows from one cavity to another cavity via some narrow gaps, at this time, the friction between the hole walls and oil molecules and between the throttling hole and the oil molecules form the damping force against the vibration, the vibration energy of the automobile body and the automobile frame is converted into heat energy, and the heat energy is absorbed by the oil and the shell of the shock absorber and then emitted to the atmosphere. The damping force of the shock absorber increases or decreases along with the increase or decrease of the relative speed of the automobile frame and the driving axle(or wheels), and is related to viscosity and variety of the oil.