Abstract: Four kinds of polysaccharide components(WPB_S-50,WPB_S-60,WPB_S-70 and WPB_S-80)were obtained by fractional precipitation fermentation of bran polysaccharide with ethanol of different concentrations(50%,60%,70% and 80%).By analyzing the purity,polyphenols,residual protein content,monosaccharide composition and antioxidant activity,the composition,antioxidant activity differences and the reasons affecting antioxidant activity of four kinds of polysaccharides were investigated.The results showed that the purity of 4 kinds of polysaccharide components was above 70%,and that of WPB_S-50 polysaccharide components was the highest,reaching 79.95%.All the components contained polyphenols and proteins,and the content of polyphenols and residual proteins in WPB_S-80 was significantly higher than other components(P<0.05).The four kinds of polysaccharides were composed of ten monosaccharides,such as arabinose,xylose,mannose and glucose,but the proportion of the monosaccharides was different.The antioxidant activity showed that all the 4 kinds of polysaccharide components had some antioxidant activity,and there was significant positive correlation with the content of polyphenols and proteins(P<0.05).