Abstract:The inside physical state has an important impact on the output characteristics of the hydro pneumatic suspension, wherein the change in temperature field is not negligible. According to the structural characteristics of the suspension, the mechanical model is built. Based on the heat transfer theory and with consideration of the impact of the heat capacity of the cylinder and piston rod on the suspension temperature rise, the thermodynamic model of the hydro pneumatic suspension was built by using lumped parameter thermal model method. The thermodynamic model and the non-linear output force model were combined to get the variation rules of the hydro pneumatic suspension temperature. The periodically excited test bench of the suspension was built. The loading test results and the thermodynamic model calculations show that: The oil is the main internal impact factor of the suspension temperature rise. Under the external incentives, due to the heat exchange with the external environment, the suspension temperature will gradually reach a state of equilibrium. While the trend of change in test results of the output power shows the effect of the suspension system of temperature change on hanging output force can not be ignored, and should be paid attention in the practical application.