In order to reveal the complicated dynamic characteristics of a double chamber oil pneumatic shock absorber under dynamic excitation, the dynamic mathematical model and fluid-solid coupled finite element model of the double chamber oil pneumatic shock absorber were established respectively considered the gas-liquid two-phase flow, and the dynamic characteristics of the shock absorber under shock, sinusoidal and stochastic excitation conditions were compared and analyzed. The results show that the calculation results of the finite element model of double chamber oil pneumatic shock absorber are basically consistent with the mathematical model;the equivalent dynamic stiffness is nonlinear under the impact of large displacement;the equivalent dynamic stiffness varies with the excitation amplitude and frequency under sinusoidal excitation, and the amplitude change has a great influence on the equivalent dynamic stiffness of the shock absorb. By using the fluid-solid couped method, the internal complex flow field under high speed oil flow can be analyzed, which is closer to actual situation.