Aiming at the steering stability of four-wheel-steering/driving vehicles，an sliding mode variable structure control algorithm is proposed based on the direct yaw moment． First，the relationship between the steering angles of frontand rear wheels is calculated through the Ackermann steering model，and all these angles are also calculated according to the control target of a zero sideslip angle． Then，the sliding mode variable structure control algorithm with the yaw rate and the sideslip angle as the control targets is designed to control the steering angle and driving torque of each wheel． Finally，the stability of the proposed control algorithm is proved by means of the Lyapunov method，and the software Matlab/Simulink is used to analyze the proposed control algorithm． Simulation results show that the proposed control algorithm can maintain the sideslip angle and the yaw rate within ideal ranges，and thus the steering stability of vehicles is effectively improved．