Abstract: In order to promote development of hillside tractors，404P hillside tractor was chosen as the research object，and working principle of hydraulic leveling system was analyzed.Functional relationship between height of body and total length of lifting hydraulic cylinder was also established.Simulation model of hydraulic leveling system based on AMESim software platform was built，and hydraulic operation simulation was carried out.Results showed that hydraulic system leveling time was 1.25 s when the body was inclined 4 °，2.44s when the body was inclined 8 °，and 3.6 s when the body was inclined 12 °.The hydraulic system could basically meet needs of actual operation.