There are many uncertain parameters in shock absorbers, which are induced by the manufacturing error, the wear of components and the aging of materials in real vehicle environment. These uncertainties often cause some deterioration of vehicle performance. To optimize the ride characteristic of a vehicle when the shock absorber includes uncertain parameters, the robust design method is used. In this paper, a Twin Tube shock absorber fluid system model has established on the multi-domain modeling environment. This model not only includes the commonly used parameters of the shock absorber but also takes into account the structure parameters of various valves in the shock absorber, which is more detailed and accurate than those models in the past literature. The robust design of the shock absorber parameters is successfully approached using the co-simulation technique, and the ride comfort performance of the vehicle is also improved. The orthogonal experiment is used to choose the main factors, which include 13 parameters of shock absorber. The vertical acceleration of the vehicle center of mass, the maximum displacement of the shock absorber and the forces generated by the contact between tire and the road are selected as ride comfort indexes, and the results show the better performance of shock absorber after the robust design.