In the conventional electro-hydraulic hitch control system, the method of measuring the tillage resistance could not accurately reflect the tillage resistance of the mounted plow. We analyzed the method of measuring the tillage resistance and proposed a method of measuring the tillage resistance of the mounted plow by the action signal of the hinge points of the upper link and the lower link. The tillage resistance analysis matrix was constructed using the spatial vector mechanics analysis principle. The resistance measurement system prototype was developed on the JINMA 1204 tractor. We analyzed the ill-conditions of the analysis matrix and developed a calculation program for tillage resistance. A field test of the tillage resistance measurement system was carried out, and the test result showed that the correlation coefficient between the measured value of the tillage resistance measurement system and the test value was 0.79, which showed a strong correlation. Resistance is effective. Through the calibration of the resistance measurement system, the maximum reference error between the tillage resistance measurement value and the tillage resistance test value is 5.7%, which meets the measurement requirements for electro-hydraulic hitch control of agricultural tractors.