Mining dump trucks have the advantages of high load-bearing weight and high efficiency, thus the trucks are mainly used in large construction sites such as opencast mining and transport infrastructure construction. Hydro-pneumatic suspensions are widely used in large construction vehicles due to their non-linear characteristics of stiffness and damping, which can better adapt to changes in external load excitation. In order to solve the problem that the suspension and tire components are easy to be damaged due to the high stiffness of the single-chamber hydro-pneumatic suspension (SCHPS) under the loading impact condition, a two-stage pressure hydro-pneumatic suspension (TPHPS) system is designed to meet the needs of the new type mining dump truck. Firstly, the structure and working principle of the two-stage pressure hydro-pneumatic suspension are analyzed. Secondly, the inelastic force mathematical model and damping force model of the TPHPS system are established. Finally, the TPHPS system model of the mining dump truck is established by using the AMEsim software. Through simulation and experiment, the suspension cylinder pressure, dynamic deflection, acceleration and power spectral density of the SCHPS system and the TPHPS system in the process of mineral loading are compared and analyzed, and the damping characteristics of the suspension systems are further obtained. The research results can provide reference for the design of hydro pneumatic suspension system of new mining dump trucks.