A water soluble schizophyllan (Scl)was isolated from the fungus Schizophyllum commune. Gas chromatography,periodate oxidation,methylation analysis and other experiments showed that the main chains are composed of (1-3 )linked glucose residues one third of which have side chains in position 6.The result of oxidation with chromium trioxide and IR suggested that all residues of Scl are βconfigurations. The conformation of Scl was studied by complex-formation with Congo Red,and by the measurements of optical rotatory and viscosity. Scl mainly a single-helical conformation in water solution at lower temperature. If the side chains are removed by periodate oxidation，the proportion of multiple-helical conformation will increase. The helical conformation changes into disorder coli in acid，base，and at slightly higher temperature.