Abstract: Our previous work has indicated that cultivation conditions for extracellular polysaccharide by Clitocybe gigantean are strongly affected by many internal and external factors. In this study，we use an effective two-phase statistical approach to enhance extracellular polysaccharide production. In the first phase，Plackett-Burman design was undertaken to evaluate the effects of the six factors，including initial pH，culture temperature, fermentation time，volume of medium，amount of inoculum and rotate speed. By regression analysis，culture temperature， time and amount of inoculum were found to be important for cultivation conditions for extracellular polysaccharide by Clitocybe gigantean. In the second phase of the optimization process，a response surface methodology(RSM) was used to optimize the above critical factors，and to find out the optimal concentration levels and the relationships between these factors. Based on the results of the first phase，a three-level three-factor(culture temperature， fermentation time and volume of medium) Box-Behnken design was employed. By solving the quadratic regression model equation using appropriate statistic methods，the optimal concentrations for obtain 103.58mg/100ml extracellular polysaccharide production was calculated as: culture temperature 27.05℃, fermentation time 6.92d and volume of medium93.90ml. The experimental data under various conditions have validated the theoretical values.