In order to improve the performance of automatic leveling control system of tractors in hilly and mountainous areas, based on the developed attitude adjustment mechanism of hilly mountain tractors, an automatic leveling control method for adjusting the swing angle of wheels by double closed loop fuzzy PID algorithm was proposed. The state space model of the controlled object was established, and a double closedloop fuzzy PID control algorithm was designed based on the model. The simulation analysis of the automatic leveling control system showed that the double closed loop fuzzy PID control had better performance than the double closed loop PID control, which can effectively reduce the overshoot and leveling time. A large number of dynamic and static tests were carried out. The results showed that the proposed automatic leveling double closedloop fuzzy PID control method had a leveling time of 12.5s on the slope of 15°, the maximum leveling error was less than 0.5°, and there was no overshoot phenomenon. The absolute value of the difference between the left and right rear wheel swing angles was within ±1°; at the same time, driving at a speed of 1.98km/h in a harsh working environment with high and low undulations, the tilt angle of the body can be controlled within ±3°, and the absolute difference of the left and right wheel swing angles was within ±5°. Generally, the control method proposed had better control effect than double closed loop PID control.