Abstract:This study investigated the extraction process of Sophora japonica polysaccharides（SJP） and analyzed their antioxidant activity. The optimal extraction conditions were determined using single-factor experiments and response surface optimization analysis：extraction time of 58 min，extraction temperature of 83 ℃，and a material-to-liquid ratio of 1∶14 （g/mL）. The SJP content，measured by the phenol-sulfuric acid method，was 78.4%. Antioxidant experiments revealed that the scavenging rates of SJP for DPPH，ABTS+，and hydroxyl radicals were 43.9%，25.7%，and 80.4%，respectively，and SJP also exhibited Fe3+ reducing capacity. Hemolysis experiments showed that SJP significantly reduced the activities of superoxide dismutase （SOD），glutathione peroxidase （GSH-Px），and catalase （CAT），markedly decreased malondialdehyde （MDA） levels，increased glutathione （GSH） content，and maintained oxidized glutathione （GSSG） at a relatively low level.These results indicate that SJP may act by protecting erythrocytes from free radical damage induced by 2，2′-azobis（2-methylpropionamidine） dihydrochloride （AAPH）.