This article studies the grain size distribution curves of the eolian sands and thechief features of the grain size parameters in southwestern part of the Maowusu Desert.The following conclusions are obtained.1. The eolian sands in this area are chiefly shaped by winds of two contrasting direc-tion, the Northwestern and the Southeastern, of which the former being dominate.2. The chief characteristics of the eolian sands are: sorting is excellent; transpor-tation process is uniform, with saltation dominating; and hence they can be identifiedand differentiated from the fluvial sands.3. The grain size distribution curves might be used for investigating the materialsource of the eolian sands.