The extraction condition of polysaccharide from Hirsutella sinensis by subcritical water was optimized using the response surface experiment.Then,analyze the structure and antioxidant activity of polysaccharide to provide theoretical basis for the rational development and application of H. sinensis polysaccharide.The optimal extraction conditions were that the extraction temperature was 160 ℃,the time was 35 min and the extraction flow rate was 3.5 mL/min,and the extraction rate of polysaccharide was up to 18.32% The study on antioxidant revealed that the polysaccharide had certain antioxidant activity. The results indicate that subcritical water extraction was a potential method to extract polysaccharides from H. sinensis with high yield and good antioxidant capacity.