Abstract: To isolate and purify rice bran crude polysaccharide（RBP） and improve its purity and biological activity,the RBP was precipitated by graded alcohol precipitation and four groups of ethanol precipitated RBP including RBP-40、RBP-60、RBP-80、RBP-80S were obtained,and the physical-chemical properties,antioxidant and hypoglycemic activities were analyzed and compared with RBP.The results indicated that,the contents of polysaccharide,soluble protein and uronic acid in RBP-80S group was significantly higher than that in other RBP groups（P＜0.05）.The antioxidant activity and hypoglycemic activity of 5 groups of polysaccharide increased with the increase of polysaccharide purity.RBP-80S had the highest scavenging rate of DPPH·,·OH and O₂^-· radicals,total antioxidant activity and Fe²⁺ reducing power.The inhibition rate of RBP-80S on α-glucosidase and α-amylase was up to 90.69% and 74.56%,and significantly better than other four groups of polysaccharides（P＜0.05）.Which indicated that the graded alcohol precipitation could increase the purity of RBP,and therefore improve the antioxidant and hypoglycemic activities in vitro,and provide a new way for improving the value of rice bran crude polysaccharide.