In view of the diversity of crops in the Huang-Huai-Hai area, the row spacing is large and the plant protection machinery is low in generalization and intelligence. A articulated steering unmanned plant protection vehicle with adjustable wheelbase and ground clearance was designed. The plant protection vehicle can be remotely controlled by a remote control, and after switching the automatic mode, it can track the path according to the predetermined route to realize the autonomous walking of the plant protection vehicle. A kinematics model was established for the autonomous walking mode of the plant protection vehicle, and the strategy of using heading tracking to realize the path tracking was determined, and the stability of the waist turning control was analyzed through the Lyapunov function. The extended Kalman filter algorithm of the sensor and the PID control method of the drive motor were proposed. Finally, the step response of Matlab was used to simulate and analyze the autonomous walking control system. The results showed that when the coefficients Kp=1，Ti=0.05,Td=0.01, the system response speed and accuracy can meet the needs of autonomous plant protection vehicle navigation control. Field tests were conducted with the turning radius of the work platform and the offset parameters of straightline walking. When the turning speed of the prototype was 3km/h, the minimum outer wheel turning radius was 2m, and when the walking speed was 6km/h, the average offset for 100m straight travel was 5.51cm, and the average endurance time of the plant protection vehicle under full load was 2.54h. The whole machine met the design requirements.