In the current research on the dynamic characteristics of hydro-pneumatic suspension cylinder,the elastic force is mainly modeled by the variable gas state equation,and the damping force is modeled by the thin-walled small hole theory.In the real situation,the thickness of the damping hole and the one-way valve is not thin-walled,but has a certain thickness,the thin-walled theory application will lead to the distortion of the model to a certain extent.Therefore,the damping model was established by using the theory of short-hole flow,and the dynamic model of the hydro-pneumatic suspension cylinder were reconstructed by considering the local head loss of the inlet and outlet.The mean absolute error (MAE) and root mean square error (RSME) of the two damping force models were compared with the real acceleration data of the support point on the suspension cylinder.It is verified that both models can simulate suspension vibration well in the low frequency range,but there is a significant deficiency in the medium to high frequency range.The short hole flow theory based model is closer to the true value in the frequency domain.