To investigate the influence of the parameters of the hydraulically interconnected suspension on the responses of a vehicle, a 7-DOFs (degrees of freedom) frequency domain model of the vehicle coupling with hydraulically interconnected suspension was established, and the frequency response function of roll angle acceleration, pitch angle acceleration, vertical acceleration on the center of mass, and vertical force on left-rear tire were then deduced. The parametric effects of the hydraulically interconnected suspension including the system oil pressure, volume of the accumulators, the differences and ratios between the areas of the two chambers of the cylinders on the dynamic response characteristics of the vehicle were evaluated. The results show that the system oil pressure has the adverse correlation with the volume of the accumulators on the frequency domain responses, the differences between the cylinder areas play a significant role on the responses, and the ratios between the cylinder areas have a certain effect on the responses of the roll angle acceleration and the tire forces but limited effect on the others. The performance test of the vehicle was taken to verify the simulation model, which shows that the influences of the key parameters on the frequency response characteristics of the vehicle are in a good accordance.