A proportional controller for the electro-hydraulic hitch system was developed based on the microprocessor MC9S12XS128 of Freescale. According to the analysis of the structure, type and characteristic of present proportional controllers for the hitch system, the controller architecture was put forward following the control requirements. The software was designed in the environment of CodeWarrior, and the PID control algorithm was adopted to realize three control modes including traction, position and mixed control for hitch system. By taking the heavy tractor with electro hydraulic hitch system as the test platform, the field experiment of the proposed proportional controller was carried out, the response time of traction control was 3.89s while 0.81s of position control. The results showed that the proportional controller for hitch system comprehensive control in high-power tractor possessed of the features of rapid response, high precision, strong stability, etc. Meanwhile, it can not only improve the field operating efficiency in the guarantee of ride comfort and working quality of tractor, but also can reduce the driver’s labor intensity.