At present, the research on vehicle trajectory tracking control has made some achievements. However, due to the poor adaptability of the control algorithms under different working conditions, there are still large tracking errors. In order to improve the adaptability, tracking accuracy and robustness of intelligent vehicles, an adaptive PID control method based on Model Reference Adaptive Control system (MRAC) is proposed. An adaptive PID control method based on MRAC is obtained by using 3 parameters of the output error of the vehicle model and the reference model. The simulation results in MATLAB show that the maximum lateral tracking errors of the adaptive PID based on MRAC in the 2 working conditions are 0.036 m and 0.076 m respectively. Compared with the traditional PID control model, the control accuracy of the control model is improved by 52.10% and 11.76%, which shows better lateral trajectory tracking performance.