Abstract: Extraction of polysaccharide from Cordyceps sobolifera in Zhejiang was investigated, and the calculation method of the extraction yield was determined. With water as extraction solvent, the effect of extraction temperature, extraction time, solid-liquid ratio and extraction times on the yield of polysaccharide were optimized with single factor test followed by four factor-four level orthogonal experiment. The result showed that the effect of the investigated factors on the polysaccharide extraction yield was in the order as extraction temperature>extraction times>solid-liquid ratio>extraction time. The optimal extraction conditions of polysaccharide were that extraction temperature of 90℃, solid-liquid ratio of 1∶40 (g∶mL) , extraction time of240min and extraction 4 times. Under these conditions the polysaccharide extraction yield was 11.82%.