A set of automatic navigation system for rice harvester with dual-motor crawler chassis was designed and tested to solve problems of high rolling rate， poor alignment stability of manual-operated crawler harvester and low field operation accuracy of existing electric crawler machinery for ratoon rice harvesting in the first season. Based on the dual-motor crawler chassis self-designed for the rice harvesting， the relationship between the steering radius of the chassis and the speed of the driving motors on both sides was derived on the basis of the field slip model. An automatic navigation fuzzy controller was designed. The dual-antenna RTK-GNSS is used to obtain the real-time position and heading angle information of the dual-motor crawler chassis. The lateral fuzzy correction controller of the automatic navigation system and the PID controller of the motor speed on both sides control the motor speed in real time to realize the automatic tracking of the working path. The results of road test showed that the average lateral deviation of the automatic navigation system was 0.015 m and 0.021 m when the dual-motor crawler chassis was driven at 0.6 m/s and 1.0 m/s. When the driving speed was 0.6 m/s， the average lateral deviation of the automatic navigation system was 0.050 m. Compared with the navigation system modified with electronically controlled hydraulic steering， this navigation system has precise control volume， fast response speed and small tracking error. It can be used in the row-to-row operation of ratoon rice in the first season to reduce the rolling rate.