Abstarct: A new water-soluble polysaccharide with molecular weight of 43 kDa and a specific optical rotation of +181◦ was extracted from the roots of Astragalus Curvirostris by warm water method (60◦C). Purification of the polysaccharide was carried out by DEAE-cellulose and Sephadex G-100 column chromatography. The total sugar of purified polysaccharide was 98.9 % and negligible content of protein and polysaccharide were observed in it. Monosaccharides analysis revealed that the purified polysaccharide of A. Curvirostris roots was composed of Glucose and Xylose with a relative molar ratio of 17.2:1.0. Structure identification of polysaccharide were elucidated by a combination of methylation, partial acid hydrolysis, GC–MS analysis, periodate oxidation and Smith degradation, FT-IR and NMR spectroscopy. The data obtained indicate that main chain consisted of (1→4)-lixnked αlpha-D-glucopyranosyl residues, with branches at O-6 it is structure consist of non-reducing terminal beta-D-Xylopyranose approximately every 17 residues.