Abstract: An intelligent vehicle-road model was established based on vehicle dynamics and it was transformed to an error-based equation in state space by linear transformation. According to the sliding mode variable structure control theory, the automatic steering control algorithm with exponential reaching law was proposed. Then the effect of reaching law parameters on system dynamic quality was analyzed in detail and a novel method to select the reaching law parameters was proposed. Simulation was conducted to validate the proposed algorithm. The results show that the developed automatic steering sliding mode algorithm not only follows the road with small error, but also improves the vehicle dynamic performance.