Abstract: The effect of carbon sources, nitrogen source and mineral salt on extracellular polysaccharide production by submerged fermentation medium of Agaricus bisporus had been studied.On the base of single factors experiments, response surface analysis was applied to optimize the submerged fermentation medium of Agaricus bisporus for extracellular polysaccharide production.The quadratic regression analysis was applied to get the optimal level of main factors, and optimal quality concentrations of the variables were obtained as follows:glucose 35.7g/L, KH 2 PO 4 2.1g/L and peptone 3.1g/L.Under these optimal conditions, the predicted and experimental production of extracellular polysaccharide was high up to 1.86g/L and 1.87g/L, respectively.