There is increasing demand for sorghum at the domestic and international market due to many ethnic and dietary foods, snacks and other products with excellent properties appreciated by consumers. The identity- preserved foods are stimulating significant interest and demand for food products from sorghum. However, the major limitation in producing excellent products from sorghum has been lack of consistent supply of good quality grain for processing. This work was undertaken to determine crop-machine parameters influencing cleaning of sorghum in a stationary grain thresher. The specific objectives were to determine some physical and aerodynamic properties of sorghum grain and its constituents influencing cleaning. A mathematical model for describing the crop-fluid-machine interaction in the cleaning process was developed and optimized. Sorghum variety, SAMSORG 17(SK 5912) was selected as test crop due to its economic importance and growing market demand in malting and baby food industries as well as other agro-based industries.