In view of the complex terrain and poor terrain adaptability of the traditional electro-hydraulic hitch control system, a set of terrain-adaptive control system for electro-hydraulic hitch of hillside tractors with adjustable lateral attitude was designed. According to the requirement of terrain-adaptive control operation of hillside tractors, a new type of terrain-adaptive hitch mechanism was designed by adding a hydraulic driving rotary device on the basis of traditional hitch structure. Based on hydraulic multi-point power output technology, a closed core hydraulic control system with load feedback was designed and a control method based on the classical PID algorithm with dead zone was proposed. Through the analysis of the working principle of the valve controlled asymmetric hydraulic cylinder, the mathematical model was established and the transfer function of the copy control system was derived. The dynamic model of the electro-hydraulic hitch terrain-adaptive control system was established by Matlab/Simulink and the simulation analysis was carried out. The simulation results showed that under the action of 0°~11°step signal, the adjustment time of the system was about 0.4s, with almost no overshot. After the system stabilized, the lateral inclination of agricultural implements was about 11.1°, and the steady-state error was about 0.1°, which verified the effectiveness of the proposed control algorithm. The traditional tractor hydraulic hitch was modified by converting the original handle control hydraulic hitch into an electro-hydraulic hitch control system with a virtual terminal, and a copy control test bench was built and an indoor bench test was carried out. The test results showed that the adjustment time of the system was about 2.2s, with almost no oversetting. After the system was stabilized, the lateral inclination angle of agricultural implements was about 11.2°, and the steady state error was about 0.2°,which was within the range of 0.5°, allowed by the system. The test results verified that the designed electro-hydraulic mounted terrain-adaptive control system of the tractor can adjust quickly and stably and meet the requirements of contour slope operation of the tractor.