The vehicle-generated road damage can be effectively reduced when the relevant parameters of hydro-pneumatic suspension in engineering vehicles are tuned reasonably. Multi-body dynamics model with ADAMS，hydraulic system model with AMESim and spectra of road surface roughness model with Simulink were established based on 4-DOF signal-axis vehicle model with consideration of the nonlinear characteristic of accumulator, fluid resistance, check valve and pipeline in the system. “95 percentage fourth power aggregate force” was used as the criterion for road-friendliness and co-simulation was achieved. The relation between road-friendliness and relevant parameters of interconnected hydro-pneumatic suspension was analyzed through co-simulation. In certain extent, the road damage coefficient first decreased and then increased with the increase of the initial pressure of accumulator and the diameter of damper hole in suspension cylinder. The road damage coefficient decreased with the increase of the total volume of accumulator and the inner diameter of pipe. The length of pipe had little influence on the road damage coefficient.