A polysaccharide (BRP) was obtained from Blumea riparia, by hot water extraction, deproteination using Sevag method, precipitation with ethanol, and fractionation through DEAE-cellulose column, Sephadex G-200 and Sepharose 6 F.F. Gel filtration chromatography. Based on UV and IR spectrum, HPLC, HPGPC and GC-MS chromatography, NMR (¹H NMR, ¹³C NMR, HMQC, HMBC) technology and methylation reaction, the structure of BRP was identified. The results showed that BRP was hightly purified with average molecular weight of 3.3×10⁴ Da determinted by HPGPC. And it was composed of Fru by HPLC analysis. The backbone of BRP had a consisting of 1,2-linked β-D-fructofuranosyl residues. Finally, the structure of BRP was fixed on as: β-D-Fruf-(2[→1)-β-D-Fruf(2→]_n-1)-β-D-Fruf.

Key words: polysaccharide (BRP), isolation, NMR, methylation, structure characterization