Abstract: Palysaccharides, PIB-Ⅰ, PIB-Ⅱ-A, PIB-Ⅱ-Band PIA-Ⅰ, were prepared in our laboratory. Their purity and molecular weight (w) were determined by high performance gel permeation chromatography (HPGPC). The HPGPC system consisted of a two -column set, Bio-Gel TSK-50 and TSK-40 columns. 0.2 mol/L phosphate pH 6.0 buffer and 0.1 mol/ L Tris-HCl pHS.0 buffer were used as mobile phase, respectively. The void volume and total volume were measured using dextran T-2000 and glucose. "The w of samples were determined from the standard curves which were made by standard dextran T-series. In two different mobile phases, the deviations of Mw were less than 6.0%, which showed that the method is highly sensitive, accurate, reproducible and rapid.