In order to obtain the best process for rice husk combustion, the morphological characteristics and composition of rice husk ash （RHA） were studied by changing calcination temperature and residence time. The research on morphology characteristics showed that the carbon content of RHA was lower when adopted the mode of first lower temperature combustion then higher temperature combustion. The microscopic morphology of RHA was different by using different calcination methods. The particle size of RHA by direct higher temperature combustion was significantly larger than that by other methods. For the component of RHA, the main ingredient of RHA was amorphous SiO2 by lower temperature（575℃）combustion while silica form crystal when preparation process existed in higher temperature（815℃）combustion stage, and the potassium content of RHA was relatively lower by using the mode of first lower temperature combustion then higher temperature combustion. 