Autonomous vehicles should have the ability that could independently complete steering operations, but traditional electric power steering systems cannot satisfy this function. In order to achieve the purpose of automatic steering of autonomous vehicles,the vehicle steering system is designed to meet both the driver’s driving and the vehicle’s automatic driving conditions,key parts of the system are selected and designed; The mathematical model of the steering system is established according to different driving conditions,and simulated in Matlab/Simulink environment. The simulation results show that this steering system can satisfy the automatic driving conditions,and can guarantee the stability of the vehicle,but due to the error between the output value and the input value of the steering system,there is a certain deviation in the trajectory.