Abstract: To attain a study in some depth for the stability of control in four-wheel-steering of vehicles the steering characteristics of a four-wheel-steering vehicle is numerically simulated in the light of automatic control where the object of control in four-wheel-steering is the zero side-slip angle of the center of gravity of the vehicle under consideration. Computer simulation of influences of vehicle speed, cornering stiffness of tire, mass of the whole vehicle and position of the gravity center upon the steering stability is carried out. The four-wheel-steering prototype vehicle is described and used in validation test. The research results show that the four-wheel-steering is of benefit to the steering stability of high speed vehicle on the whole, yet attention must be paid to the deteriorating tendencies caused by changes in some factors.