Abstract: Grain cleaning is the core technology of cyperusesculentus harvest. Therefore, in the process of cyperusesculentus harvesting, how to enhance operation fluency and efficiency, and to ensure technical indicators such as low loss rate of cleaning, low impurity rate of cyperusesculentus pods, has been a difficult technical problem of cyperusesculentus harvester. In order to settle the above difficulties, a cleaning device was designed, realizing the grain winnowed combined with screened. Utilizing kineto-statics method, in this paper, we researched relative motion of grain on the sieve surface, analyzed limiting conditions of grain upglide, downglide, jump from sieve surface, and determined the key motion parameter in theory. In addition, based on Box Benhnken’s central combination theory, response surface tests were carried out with three factors as influencing factors, namely, the vibrating screen amplitude, vibration frequency and revolving speed of fan. The effects of various factors on loss rate of cleaning and impurity rate of cyperusesculentus pods were analyzed and the influencing factors were optimized. The experiment results show that the optimal parameter combination is the vibrating screen amplitude of 11mm, the vibration frequency of 9hz and the revolving speed of fan of 1442r/min. The field test shows that at this time, the loss rate of cleaning is 4.35% and the impurity rate of cyperusesculentus pods is 5.49%. This study can provide a theoretical reference for the design of cleaning device of cyperusesculentus harvester.