Abstract: An optimal path tracking control system was proposed to improve accuracy of wide-span robot operation platform in field and reduce lateral deviation of running caused by uneven soil quality and asymmetric geometric shape of agricultural machinery．System adopted unscented kalman filter（UKF）, integrated information of Beidou satellite positioning and machine vision, and observed vehicle running state parameters．In addition, a nonlinear model predictive control（NMPC）strategy was introduced to establish a vehicle kinematic model, which was compatible with adaptive model predictive control（AMPC）．Simulink simulation results showed that NMPC has faster response and overshoot speed for path tracking system．