Abstract: 6 kinds of corn straws from different areas and 5 kinds of different crop straws were dried naturally and grinded into powder with diameters of 0-10 mm to study the physical properties of the crop straws. The results showed that densities of the natural and compressed crop straws were 37.43-140 kg/m3 and 48.40-200 kg/m3 respectively, the static and dynamic stacking angles were 44°-51° and 17°-31° respectively. The static friction coefficient between crop straws and metal or rubber was 0.45-0.55 or 0.51-0.62, and the coefficient of internal friction was 0.53-0.73. The stacking angles and the bulk densities were different for different kind of the crop straws or straws from different areas. The bulk density was affected by the kind and the uniformity of the crop straws. The difference of bulk density between different kinds of crop straws was very huge. The more the water was in the crop straws, the bigger the stacking angle was. There was no change of the friction coefficient and flow property. It could be inferred that the difference of the area and the kind of the crop straws should be fully considered when the crop straws were compressed, delivered and stored. This study can provide basic data support for the use of crop straws.