Abstract: At present, there are few studies on the influence of the cleaning parameters of soybean harvester on the cleaning indexes in China. In order to change the current situation of soybean combine harvester, due to the lack of theoretical guidance for the parameter adjustment of the corresponding cleaning device, the cleaning parameter adjustment is not timely and accurate, resulting in high loss rate and high impurity content of soybean harvester. In this study, the multi parameter adjustable and measurable cleaning system was used to optimize the cleaning parameters of soybean harvester in field test. The influence rules of the five cleaning parameters on the two cleaning indexes were analyzed, and the best cleaning parameter combination was found. The field verification test of the best cleaning parameter combination of soybean harvester was completed. Based on the analysis of the structure of cleaning system and the principle of cleaning operation of soybean harvester, the importance of the operating parameters and operating speed of cleaning device to the cleaning indexes of soybean combine harvester was obtained. The operation speed, opening of chaffer screen, damper opening, fan speed and crank speed of shale shaker were used to optimize the five cleaning parameters in field experiments. Cleaning loss rate and impurity rate were used to optimize the two cleaning indexes of field experiments. Through the analysis of the influence of cleaning device on the indexes of soybean combine harvester, the cleaning loss rate and impurity rate were determined as cleaning indexes, and in the field experiment, the cleaning loss of samples were collected in the form of binding cleaning loss receiving bag at the back of cleaning room to optimize the parameters of cleaning loss in the field experiment. Response surface test design and data analysis are completed by using design expert software. The contribution rate and response effect of each parameter on the two cleaning indexes were analyzed by the contribution rate method and response surface diagram. The results showed that the order of influence of cleaning parameters on cleaning loss rate was crank speed of shale shaker, fan speed, operation speed, damper opening, opening of chaffer screen. The order of influence of cleaning parameters on the impurity rate was opening of chaffer screen, damper opening, fan speed, operation speed, crank speed of shale shaker; The results showed that when the cleaning loss rate was small and the impurity rate was small and the feeding amount was large, the optimal cleaning parameters were operation speed was 6 km/h, opening of chaffer screen was 32 mm, damper opening was 17°, fan speed was 1 310 r/min and crank speed of shale shaker was 410 r/min. At this time, the cleaning loss rate was 0.25%, the impurity rate was 0.61%, and the relative error with the optimized value of the model was 0.250% and 0.113%, respectively. Compared with the cleaning indexes of the field experiment of soybean combine harvester under the common cleaning parameters, the cleaning loss rate was reduced by 0.05%, and the impurity rate was reduced by 2.09%. The results provide a theoretical basis for the setting and adjustment of cleaning parameters and the research and development of self-adaptive cleaning system.