Abstract: Abstract: In response to the problems of low impurity removal rate, high potato injury rate, and high breakage rate of the existing potato combine harvester cleaning device, this study designed a cleaning device based on a bagged potato combine harvester for viscous soil conditions. The two rollers rotated at different speeds to clean potatoes by rubbing. Box-Benhnken response surface experimental design theory was used to conduct an orthogonal test. The feeding volume, device inclination, cleaning roller speed, smooth roller speed, roller distance, and relative height were selected as the testing factors. The potato injury rate, breakage rate, and impurity removal rate were selected as the evaluation indexes. The regression mathematical model between each influencing factor and index was established, and the interaction effect of each factor on the response value was analyzed. At the same time, the model was comprehensively optimized. When the feeding rate was 4.3 kg/s, the device inclination angle was 10.3°, the cleaning roller speed was 119 r/min, the smooth roller speed was 148 r/min, the roller distance was 16.8 mm, the relative height was 40.5 mm, the potato injury rate was 1.06%, breakage rate was 0.54%, and impurity removal rate was 96.15% respectively. Field verification tests were conducted on the optimized results. Under the combination of optimal parameters, the potato injury rate was 1.10%, the breakage rate was 0.55% and the impurity removal rate was 95.04%. All evaluation indexes were close to the predicted values and met the operational performance requirements of potato combine harvesters. The study is beneficial to the structural improvement and operation parameters optimization of the cleaning device for potato combine harvester.