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Aiming at the problem that the driver's sitting posture changes due to the cockpit tilt during the tractor ploughing operation on high and low ridges, which affects the driver's ride comfort, a tractor seat leveling control system based on the driver's comfort was designed, a seat leveling control strategy based on the driver's ride comfort was proposed, and a seat leveling system controller was developed to feed back the seat tilt state in real time according to the seat angle sensor. The automatic leveling of the seat was realized. In order to better improve the driver's riding comfort in the leveling process, a test-bed simulating the tilt state of tractor seat was built, and the influence of seat tilt on the driver's upper torso posture under different angles in the test-bed was studied. The test results showed that the projection offset of human thoracic spine and lumbar spine was increased with the increase of seat tilt angle, but the projection offset when the seat was tilted at 3° was far less than that when the seat was tilted at 5°, which determined the operating threshold of the seat leveling system. Through the subjective evaluation test, it was determined that the driver's comfort was higher when the speed of seat leveling was 6~8mm/s. Finally, the real vehicle test was carried out on Dongfanghong LX754 tractor. The comparison test of driver's back muscle electromyography evaluation showed that the lumbar force was uniform compared with that without adjustment, which can well protect the driver's lumbar muscle. The tractor operation accuracy test and the tractor straight-line driving path tracking test showed that the use of the seat leveling system improved the operation efficiency of the steering wheel and gear. After the seat leveling, the average error of operating the tractor straight-line was reduced by 3% and the maximum transverse error was reduced by 8%, which verified the practical value of the system. This research can improve the ride comfort of drivers.