Abstract: In view of the problem that the stiffness of suspension system composed of leaf springs, lifting lug and brackets is abnormally higher than that of leaf springs, the influencing factors of the stiffness of suspension system are analyzed, and the influence degree of each factor is simulated by using Adams/car module. Taking the front suspension system of a 6-ton light truck as an example, the influencing factors of stiffness deviation are analyzed, and the optimization measures are formulated to verify the optimization effect. The analysis method improves the design method for the development of suspension system.