Abstract: Aiming at problems of complex working environment, poor chassis stability and easy overturning of hilly tractors, a hilly tractor chassis with three-point automatic leveling mechanism was designed．A three-point leveling scheme with hydraulic cylinder automatically controlling frame balance was adopted to ensure leveling angle between −25° and 25°．Based on Simulink software, kinematics simulation analysis of leveling mechanism was carried out, and lateral and longitudinal stability of the tractor when driving and working on ramp was analyzed by using classical mechanics theory．Results showed that limit tilting angle of chassis was 55.38° in uphill, 44.03° in downhill, 25.62° in uphill and 13.18° in downhill．The oil cylinder angle ranged from 63.9° to 107.5°, angular velocity ranged from −0.2061 to −0.1535 rad/s, and angular acceleration ranged from −0.0035 to 0.0358 rad/s²．Hydraulic leveling system ran smoothly．The chassis of tractor in hilly areas could improve adaptability of tractor in mountainous areas and the safety of drivers, and has good stability．