In order to solve the problems of poor stability, low efficiency and poor driving safety and comfort of agricultural machinery operating in complex terrain such as large slope and small plot, a design scheme of automatic leveling system for the chassis of small agricultural machinery in hilly and mountainous areas was put forward, which integrated the driving system, control system and leveling actuator. A self-balancing three-point leveling system was designed. The front leveling mechanism used passive damping technology to deal with high-frequency disturbance, and the rear used double guide post servo cylinder to ensure the accuracy and stability of motion trajectory. The control system based on single chip microcomputer was developed, and the electronic control technology based on servo cylinder was used to realize the automatic adjustment of the tilting angle of the working chassis, so as to improve the stability and working efficiency of the agricultural machinery in the hilly and mountainous terrain. In order to meet the requirements of load bearing and stability of agricultural machinery in complex terrain, the leveling strategy of "fixed set point leveling method" was adopted and its movement process was analyzed. Finally, the static test verified that the system can adjust the tilt state of different initial pitch angle and roll angle to the set state of-0.2°~ 0.2 °. The dynamic test verified that the chassis tilt angle can be adjusted to-1.2° ~1.2 ° and the standard deviation was about 0.8 ° in actual work, reaching the design expectation.