Polysaccharide was isolated from the fruit bodies of Lentinus edodes and verified by ultraviolet spectrum.The proliferation of human hepatoma SMMC_7721 cell line was significantly inhibited by the treatment of 50ugml the polysaccharide.The conclusion was proved by determining the variation of the growth curve,mitosis index,and mitochondria activity.The inhibitory of the polysaccharide against implanted S_180 tumor in mice was also performed with the 52.8% inhibition.