Abstract:The shock absorber is an important part of the automobile suspension, and it plays an important role in the automobile driving process. Hydraulic shock absorber is widely used in automobile. To research the damping characteristics of hydraulic shock absorber, the structure and working principle of a hydraulic shock absorber was analyzed, and its hydraulic system diagram was set up. The mathematical model of the piston valve, bottom valve and oil cavity pressure for the shock absorber were established using the knowledge of fluid mechanics. And then the mathematical model of the stretching stroke and compression stroke damping characteristics were derived. The damping characteristic was simulated by MATLAB / SIMULINK, and it was tested on shock absorber test instrument. The results show that the model of the mathematical model is correct. Finally, the effect of the frequency on damping characteristic is tested, which provides a reference for the design and use of shock absorber.