Abstract: AimTo study the physicochemical properties and the structure of Achyranthes bidentata polysaccharide(AbPS). MethodsAbPS was isolated from the roots of Achyranthes bidentata Bl., and purified by gel filtration chromatography. The distribution of the molecular weight of AbPS was determined by ESI-MS. The structure of AbPS was deduced by methylation analysis, reductive-cleavage and ¹³CNMR spectroscopy. ResultsAbPS was shown to compose of fructose residues and glucose residues and the molar ratio was 8∶1. AbPS contain 2,1-linked fructose residue, 2,1-linked fructose residue, 1,2,6-linked fructose residue, terminal fructose residue and terminal glucose residue. ConclusionAbPS is a fructan and belong to graminan.