Abstract: Objective:To investigate the effects of polysaccharide on mice anti-fatigue effect of Rosa davurica Pall.fruit and anti-oxygen free radical level.Methods:A total of 150 Kunming male mice were randomly divided into three experimental group,and a blank control group(administered with equal volume of normalsaline)and a positive group of Ginseng decoction(0.135 g·mL^-1),a high dose group of polysaccharides(100 mg·kg^-1),medium dose group(50 mg·kg^-1),low dose group(25 mg·kg^-1),intragastric administration of 0.1 mL·10 g^-1. Exhaustive swimming time,rotarod time,blood lactic acid(BLA),liver glycogen(LG),muscle glycogen(MG),blood urea nitrogen(BUN)contents and activity of total antioxidant capacity(T-AOC),superoxide dismutase(SOD)and glutathione superoxide dismutase(GSH-Px),malondialdehyde(MDA)contents in the liver and serum were measured,which were used to evaluate the anti-fatigue and anti-oxygen free radical ability of polysaccharide. Results:Compared with blank group,rotarod time were significantly prolonged in high and medium dose group(P<0.05).Weight-loaded swimming time of each dose group were significantly increased(P<0.05). The contents of MG and LG were significantly increased in middle-dose group and high-dose group. The contents of BUN in high-dose group were decreased. The content of BLA in high-dose group were significantly decreased(P<0.05)in middle-dose group and high-dose group(P<0.05).The activity of SOD in liver and serum of mice in high dose group were increased significantly(P<0.05)and the activity of SOD in liver of mice in medium dose group were increased significantly(P<0.05). The contents of MDA in serum of mice in medium dose group were decreased significantly,and that in liver and blood of mice in high dose group were decreased significantly(P<0.05). The ability of T-AOC were all increased in middle-dose group and high-dose group(P<0.05). The activity of GSH-Pxin liver and serum of high dose group were increased significantly(P<0.05). Conclusions:Polysaccharides from Rosa davurica Pall. would have good anti fatigue and anti oxygen free radical effects.