This paper took an SUV vehicle as the prototype, established a frequency-domain model of vehicle with KDSS-fitted, based on the transfer matrix method to derive the impedance matrix of hydraulic subsystem, solved the eigenvalue in numerical optimization iteration method, compared and analyzed the modal parameters of KDSS-fitted vehicle, ARB-fitted vehicle and no-ARB-fitted vehicle model. The results indicate that KDSS is able to effectively reduce the roll motion of sprung mass in the same way as anti-roll bar, and simultaneously maintain the ride comfort performance. At the same time, the wheel torsion stiffness, compared with ARB, is greatly reduced. This gives the wheels full contact with the ground and improves the passing ability of the vehicle.