Abstract: In order to make sure the influence of main parameters on the performance indexes of expander, this article tested and analysed the influence of essential parameters—N spiral rate, L screw-pitch, Δ gap, M_e % moisture of rioe husk—on the performance indexes of expander, e.g. Q productivity, q production per watt, and P pressure expanded with the design method of reggressive rotation. Then set up the mathematic model with the indexes of production per watt etc. After the optimal design with the essential indexes parameters was determined, then the performance indexes of the expander can be made to meet the optimum option.