Objective: To study the antioxidation of polysaccharide extracted from Fructus Gleditsiae abnormalis. Method: The scavenging activities of the polysaccharide in vitro on hydroxyl radical (·OH)

superoxide radical (O2-·) and hydrogen peroxide (H2O2) were investigated by modified chemical systems. Result: The polysaccharide with 50% alcohol precipitation of the relative molecular mass of 5 000-100 000 performed the scavenging activities on superoxide radical higher than Vit C. Polysaccharide with 30% alcohol precipitation of the relative molecular mass more than 10 000

polysaccharide with 50% alcohol precipitation of the relative molecular mass 5 000-10 000

polysaccharide with 74% alcohol precipitation of the relative molecular mass more than 5 000 and polysaccharide with 88% alcohol precipitation presented hydroxyl radicals scavenging increasing with concentration increasing in 0.00-1.00 g·L-1 range. Also the largest scavenging rates were all more than 90%. The polysaccharides from Fructus gleditsiae abnormalis also showed certain scavenging activities on hydrogen peroxide

74% alcohol precipitation polysaccharide with relative molecular mass more than 5 000 scavenged 20.18% of hydrogen peroxide at 0.07 g·L-1. Conclusion: The polysaccharide extracted from Fructus Gleditsiae abnormalis can scavenge·OH

O2-·and H2O2 effectively. The antioxidant potential of polysaccharides from Fructus Gleditsiae abnormalis is presumably related to their relative molecular mass.