In this paper, the nonlinear governing equations was established for a threeaxis heavy vehicle model with the interconnected hydropneumatic suspension. Considering three pavement conditions including impact incentive, random incentive and sine incentive, the nonlinear dynamic responses of the vehicle were studied in detail. The effect of the interconnected hydropneumatic suspension on the behvaiour of the three axis heavy vehicle were also discussed. For the case of road sinusoidal periodic excitation, the bifurcation diagram, the waveform, phase portrait, Poincare map and power spectrum are presented with the different road roughness excitation frequency. Numerical results showed that there exist periodic motions and chaotic motions for the heavy vehicle system. And it is beneficial for shock absorption of multiple axis heavy vehicles by using inter-connected hydro-pneumatic suspension.