In this paper,ophiopogon japonicus crude polysaccharide was extracted by hot water and ultrasonic extraction,then purified by DEAE-cellulose52 cellulose column chromatography and Sephacryl S-300 gel column chromatography.Homogeneous polysaccharide WPOJ-DS extracted with hot water and UPOJ-DS extracted by ultrasound were obtained.The structures of WPOJ-DS and UPOJ-DS were characterized by high performance liquid chromatography,gas chromatography,infrared spectroscopy,partial acid hydrolysis,methylation analysis and magnetic resonance imaging.The solution conformation of WPOJ-DS and UPOJ-DS were studied by congo red test,circular dichroism spectra and atomic force microscopy.The results showed that there were differences between WPOJ-DS and UPOJ-DS,which existed in the molecular weight,molar ratio of monosaccharide and the solution conformation,while the differences also demonstrated that the structure characterization and solution conformation could be effected by ultrasonic extraction.The main chains in both WPOJ-DS and UPOJ-DS mainly composed of →6)-D-Glcp(1→ and →3,6)-D-Glcf(1→.The structure of →6)-β-D-Glcp(1→ existed in WPOJ-DS but not in UPOJ-DS.Congo red experiment,circular dichroism spectra and chromatography and atomic force microscopy showed that there was a helix structure in UPOJ-DS but not in WPOJ-DS.In addition,the solution conformations of WPOJ-DS and UPOJ-DS were different in different environment solutions.