Abstract: The polysaccharide of Ligularia fischeri was extracted by water extraction and alcohol precipitation method. The extraction conditions were optimized by single factor experiment and Box-Behnken methodology. The extraction yield of polysaccharide was 8.76% under the optimized conditions with solid to liquid ratio of 1:20 (g/mL) at 90 ℃ for 2 h with three times of extraction. The structure of the extracted polysaccharide was determined by FT-IR and HPLC analysis. The HPLC analysis illustrated that deproteinated polysaccharide from L. fischeri comprised of galacturonic aid,rhamnose,galacturonic,arabinose,mannose,glucose,gluconic acid and fucose with percentages of 43.5%,6.0%,23.6%,11.5%,6.3%,5.4%,1.6% and 0.9%,respectively.

Key words: Ligularia fischeri, polysaccharide, Box-Benhnken design, monosaccharide compositions