Abstract: Taking Ganoderma lucidum in Guanxian County as the experimental material, the crude polysaccharide GLP was extracted from the fruiting body of G. lucidum by hot water. After deproteinization by Sevag methods and decolorization by activated carbon methods, and then separation and purification by Capto^TM DEAE ion chromatography and Superdex 6 prep Grad gel chromatography, respectively, the homogeneous polysaccharide GLPS80a was obtained. And its average molecular weight was 9024 Da. Its chemical structure was preliminarly characterized by monosaccharide composition analysis, infrared scanning and nuclear magnetic resonance analysis, respectively. The results showed that GLPS80a was composed of fucose, glucosamine, galactose, glucose, xylose, mannose and gluconal, and the molar percentage was 0.06:0.23:0.17:1.00:0.08:0.19:0.23. It was an acid polysaccharide with the main of pyranoid glucose linked by β-D-(1,6) glycosidic bond and did not have a triple helix structure. The antioxidant results indicated that GLPS80a had scavenging ability of DPPH radical, ·OH radical and ABTS⁺ radical. Their EC₅₀ was 7.40, 8.74 and 0.33 mg/mL, respectively, and the reducing power RP_0.5AU was 8.33 mg/mL. This work would lay a theoretical foundation for development of G. lucidum resources in Guanxian County.