In order to adapt to the multivariate environment of soil condition, a control algorithm based on soil specific resistance for force-position mixed control was explored. By building fuzzy PID control strategy, soil specific resistance B was introduced to simulate soil environment, and Matlab was used to analyze the specific resistance of different soils. Based on the system overshoot, stability time and change of tillage depth, combined with practical experience, the relationship between weight coefficient and soil specific resistance was discussed, and the control algorithm of weight coefficient was designed by the relationship. The method was compared with the method with fixed coefficient of 0.5, and the field tests were carried out. The experimental results showed that the method of variable weight force-position mixed control using this control algorithm can take advantage of position adjustment in the soil with smaller resistance, so as to ensure the depth of tillage;in the soil with larger resistance, the advantages of force adjustment can be taken to ensure the performance of the engine. The method can realize the automatic judgment and setting of the weight coefficient in the area where the soil specific resistance changed greatly, and laied the foundation for the more accurate control of the system, which can also have implications for researchers in the field.