The main structure and working parameters of the cleaning device of oil sunflower combine harvester were determined through the kinematic analysis of the mechanism and the force analysis of the material, in view of the problems of high seed trash rate and loss rate of the cleaning operation in the process of oil sunflower combine harvesting. The results of the single-factor test showed that the optimal working range of the cleaning device was 1100~1300r/min for fan speed, 3~5Hz for vibration frequency and 20°~40° for the inclination angle of the wind separator. The Box-Behnken test was designed, the response surface regression model was established, and the parameters were optimized. The results showed that the order of significance of each test factor on the trash content rate and the loss rate was fan speed, vibration frequency, and the tilting angle of the splitter; when the fan speed was 1200 r/min,the vibration frequency was 4Hz, and the tilting angle of the splitter was 27°, the test results showed that the trash content of the oil sunflower seeds was higher than that of the other seeds. When the fan speed was 1200r/min, the vibration frequency was 4Hz, and the tilting angle of the splitter was 27°, the test results showed that the seed content rate of oil sunflower was 4.25% and the seed loss rate was 1.82%, which meets the national standard requirements of cleaning of oil sunflower combined harvester.