Polysaccharides from sporocarp of Agaricus bisporus was extracted by using methods of hot water lixiviation,ethanol precipitation,Sevag's deproteination and ethanol precipitation again.Extraction temperature,extraction time,ratio of water to raw material and extraction times were selected in single-factor tests.Based on the single-factor tests,combination of the extraction parameters was optimized by using four-factor-three-level orthogonal test.The optimum conditions were extracting temperature 80 ℃,extracting time 4 h,ratio of water to raw material 50 mL/g and extraction times 3.Practicing this optimal condition,extraction yield of polysaccharides from sporocarp of Agaricus bisporus was 3.510 5%.In crude polysaccharides of Agaricus bisporus sporocarp,carbohydrates content,determined by applying the phenol-sulfuric acid method,was 71.84%.Relative viscosity(to deionized water),detected by using Ubbelohde viscosimeter,was 1.109 6 at temperature of 25 ℃ and concentration of 10 mg/mL.In FTIR spectrum obtained from KBr pellet method,characteristic absorptions(3 700~3 100 cm-1 and 3 000~2 800 cm-1) of polysaccharides were observed clearly.