In order to enhance the stability of vehicle in limited driving conditions, a virtual prototype model of four-wheel-steering vehicle which included suspension system, steering system and nonlinear characteristics of tires was established by using ADAMS/Car software. Control objectives of the best performance of side slip angle and yaw rate were settled. Aiming at the nonlinear characteristics of vehicle, an integrated fuzzy control strategy of rear steering angle and yaw moment was proposed, and a nonlinear integrated fuzzy control system was designed. Adopted the co-simulation method of ADAMS/Car and Matlab/Simulink, various simulations in limited driving conditions were carried out and the performance of the designed control system was tested. The simulation results showed that the integrated fuzzy control of rear steering angle and yaw moment could effectively avoid the instability of vehicle during critical steering process.