Abstract: The utilization of rice straw can protect the environment and contribute to sustainable development. The distribution and morphology of silicon dioxide from rice straw was investigated with SEM-EDXA, and the nano-silicon dioxide was prepared from rice straw with pyrolysis processing. The results showed that, the silicon was distributed in granular zone of the surface of rice straw in the form of silicon dioxide, and the content was 12.8%. After thermomechanical refining, the silicon dioxide content was remained above 8%, and the dimension of silicon dioxide in the surface of fiber decreased. The dimension of silicon dioxide increased with increasing the pyrolysis time from 2 to 4 h, as while as increasing pyrolysis temperature from 575 to 775℃. After ball milling processing, the granule dimension of silicon dioxide was reduced from 18.94 to 6 μm. Furthermore, the proportion of granule dimension under 100 nm was increased. The processing parameters with pyrolysis temperature of 575℃, time of 2h and ball milling time of 10 min were suggested for nano silicon dioxide production.