In this study,the chemical properties,structure and monosaccharide constituents of Durvillaea antarctica were analyzed. The polysaccharides were extracted by microwave and precipitated by ethanol after removing protein by Sevag method. Then the polysaccharides were separated and purified by ion exchange and gel filtration chromatography into uniform polysaccharide HRCS. The structure of Durvillaea antarctica polysaccharides and monosaccharide constituents were analyzed by HPLC,ultraviolet spectrum,infrared spectrum and gas chromatography. The result showed that HRCS with a molecular mass of 1. 79 × 105Da,contained no protein and nucleic acid,it mainly contained α-glycosidic bond and β- glycosidic bond with pyranose. Durvillaea antarctica polysaccharides HRCS contained 3 types of monosaccharide: L-fucose,D-galactose and D-glucose,their molar ratio was 2. 18∶ 0. 82∶ 1.