An automatic navigation control system based on controller area network was designed on Dongfanghong X-804 tractor, which includes the navigation controller, GPS system, steering system and CAN communication system. The navigation controller, which used ARM processor AT91SAM9261 embedded CPU, was used to realize automatic navigation control based on double closedloop PID algorithm, and the CAN interface circuit was designed by using a control chip transceiver SN65HVD1050D. The function nodes realized steering control, speed control, brake control, and machine lift control respectively. Then, a communication protocol of CAN2.0 was presented for distributed control network. Finally, CAN communication experiment and field test were carried out based on Dongfanghong X-804 tractor. Experimental results demonstrated that the CAN bus system was able to transfer data well, and the double closedloop control solved the control overshoot well and the average error was 0.41°, with 1.32s tracking time. The field test result showed that the average lateral tracking error of positioning was 0.021m in line tracking and 0.016m in headland turning.