Polysaccharides extracted from the stem of Atractylodes macrocephala Koidz by hot water,were fractionated by DEAE-52 cellulose chromatography,and purified by Sephadex G-200 gel filtration chromatography to obtain a fraction, named WAM-1. HPLC and GC analysis showed that WAM-1 was a homogeneous and consisted of glucose and galactose in the molar ratio of 3. 01: 1. The molecular morphology of WAM-1 was observed under an atomic force microscope (AFM).The results showed that WAM-1 existed in different forms with different concentrations. The concentration of polysaccharide had effects on the conformation and form of chain interactions, which might be related to the interaction of intramolecular and intermolecular hydrogen bonds. At 10 μg/mL,the morphology of WAM-1 was observed clearly in rigid chains with many branches.