Ganoderma lucidum polysaccharides were extracted by boiling water from the fruiting bodies of red ganoderma lucidum,then protein was removed by Sevage reagent,with ethanol precipitation,run water dialysis, centrifugation and freeing-drying. Monosaccharides were acetylated and quantified by external standard,and the polysaccharidesthe amount of total carbohydrates was determined by phenol-sulfuric acid method. The monosaccharide constituents,structure and Mw distribution were analyzed by UV-Vis,IR,GC,GC-MS and HPSEC with ELSD. The results demonstrated that ganoderma lucidum polysaccharides were beige,the yield was about 2%,and the content ≥43%. IR spectrometry showed that the structure of ganoderma lucidum polysaccharide was pyranoid glucan with β-glycosidic bond. The quantitative result of external standards indicated that the monosaccharide constituents were mainly composed of glucose,at about 89% percent,and contained a small amount of D-arabinose,D-xylose,D-mannose and D-galactose. It was a homogeneous polysaccharide with the amorphous structure,attributed to biological macromolecules,its Mw distribution was at 80-2 000 Kda,and a primary Mw at 2 000 Kda.