The present paper introuduces the method, with which the water-soluble polysaccharide was extracted with hot water from Garidi-15, the products were further purified with column chromatography on SephadexC-25, and the contents of water soluble polysaccharide were determined by phenyl hydrate-sulfuric acid method. The average recovery was 100.50%, and RSD was 0.82%. The components of water soluble polysaccharide were identified by gas chromatography as xylose, mannose, galactose and glucose in the molar ratio of 1.03 : 1.26 : 0.77 : 2.30. The water soluble polysaccharide was identified by IR spectrum and UV(200-400 nm) scanning spectrum. The IR spectrum indicates that there are characteristic absorption peaks of polysaccharides at 3 417.46, 2 928.65, 1 742.86, 1 643.69, 1 149.78, 1 078.19, 1 022.56 and 834.57 cm(-1), of which there are absorption peaks of pyranose at 1 078.19 and 1 022.56 cm(-1), and contain one characteristic absorption peak of alpha-pyranose indican band at 834.57 cm(-1). The UV scanning spectrum shows the obvious polysaccharide absorption peak at 280 nm, and indicates the existence of C=O bond.