Abstract:To investigate the structure and antioxidant activity of Lycium barbarum polysaccharides， crude Lycium barbarum polysaccharides （LBPs） were extracted by water extraction and alcohol precipitation and then purified by a DEAE-52 cellulose ion-exchange column to obtain purified Lycium barbarum polysaccharides（LBP 1）. Total sugar， uronic acid， protein， and starch content， ultraviolet （UV） spectroscopy， monosaccharide composition analysis， and methylation analysis were performed on LBP 1 to determine its structure. The results showed that the total sugar content of LBP 1 was 70.95%， and the uronic acid content was 33.60%. The monosaccharide composition were Ara， Gal， Glu， Rha， Man. Methylation results showed that LBP 1 had 9 glycosidic bonds， which were Araf-（1→、→5）-Araf-（1→、Glup-（1→、Galp-（1→、→3，5）-Araf-（1→、→3）-Galp-（1→、→6）-Galp-（1→、→3，4）-Galp-（1→、→3，6）-Galp-（1→. The antioxidant activity results showed that the scavenging rates of LBP and LBP 1 on DPPH free radicals were 51.2% and 86.4%， respectively； the scavenging rates on ABTS+ free radicals were 87.15% and 91.15%， respectively. These results indicated that LBPs had high antioxidant activity， and the free radical scavenging rate of LBP 1 was higher than that of LBP.