Abstract: The residual mushroom of Hypsizygus marmoreus was used to extracted polysaccharides by hot water extraction method. Response surface methodology was used to optimize the hot water extraction process. A regression model for predicting the yield of polysaccharides was formulated and validated. The effect of the independent variables and their interactions were studied. The optimal process conditions were obtained as follows:extraction temperature 90℃, extraction time 2.5 h, liquid-solid 38:1 mL/g. Under these conditions, the maximum yield of polysaccharides was 10.01% experimentally, which was in good agreement with the model prediction, indicating that the model is feasible. The results of this paper will have significant effect on the processing and related research.