The working principle and the valve train characteristics of the developed variable damping shock absorber are analyzed.According to the hydromechanics theory,a mathematical model of the variabledamping shock absorber is established through MATLAB and the calculation formula is deduced.The FS curve and FV curve are obtained through computer simulation.According to QC/T545 national standard,external characteristic curve is obtained by bench test.The simulation result is compared with the experimental data and the correctness of the mathematical model is proved.The model accurately describes the variation of damping force with the displacement and can be used for shock absorber design and performance prediction.