Abstract: To study the vibration reduction charaterstics of viscoelastic suspension system of crawler-type vehicle, the model of suspension system was built for two-degrees-of-freedom nonlinear osciliation according to its structural feature and nonlinear behavior. The approximate analytic solution of movement system was derived using the averaging method in the natuaral frequency section. Taking a 300 kW tracked tractor mounted with viscoelastic suspensions for instance, the nonlinear resonance characteristics and the performance of vibration damping reduction were investigated in the natuaral frequency section of vehicle system. The relationship between the nonlinear resonance charaterstics and system parameters, including the excitation amplitude, the stiffness and damping coefficients of viscoelastic suspension, the ground stiffness and the mass of vehicle body and suspension, were numerically analyzed. And the suggestion were given to improve the performance of vibration reduction. The model and analysis method are applicable to the matching design and optimization of viscoelastic suspension system.