Abstract: Four factors quadratic orthogonal rotation design was used to investigate the influencing factors on the yields of polysaccharide from Lentinus edodes waste substrate such as extraction temperature， extraction time， liquid/solid ratio and alcohol precipitation ratio. The results indicated that the obtained regression equation reached the significant level without any lack of fit factor. The optimum extraction conditions were as follows: temperature 92℃ for six hours and 18 minutes， liquid/solid ratio 40∶1， and alcohol precipitation ratio of 3∶1. The yield of the polysaccharides of Lentinus edodes waste substrate was 1868 mg·g-1 under above conditions.

Key words: Lentinus edodes waste substrate, polysaccharide, hot water extraction, quadratic regression rotation\|orthogonal combination design