Abstract: Objective To observe the effects of polygonatum sibiricum polysaccharides (PSP) on free radical metabolism in brain tissue of the mice at the time of exhaustion and recovery.Methods Seventy-two Kunming mice were randomly divided into three groups:normal group(N),high (H) and low(L) dose PSP group.The mice in the H and L dose groups were administered with PSP by gavage once a day for 4 weeks and those in the N group were treated with a same amount of normal saline.By the end of the treatment,the mice of the 3 groups were sacrificed at the time of rest state,the immediate end of exhaustive exercise and 24 hours after the end of exhaustive exercise,respectively.The content of malonaldehyde(MDA),the activity of superoxide dismutase (SOD) and glutathione peroxidase(GSH-Px),and total antioxidant capacity(T-AOC)in brain tissue of the mice were measured.Results For the mice in H group,the contents of MDA (3.46±0.29 at the immediate end of exhaustive exercise,2.29±0.55 nmol/mg 24 hours after the end of exhaustive exercise)were significantly lower than those of the mice in N and L group(P<0.01,P<0.05),and the activities of SOD(100.64±10.12,114.58±9.50 U/mg),GSH-Px(2.17±0.35,2.45±0.27 U/mg),and T-AOC(0.50±0.09,0.75±0.09 U/mg)were all higher than those of the mice in N and L group.Conclusion PSP can improve antioxidant capacity of brain tissue and has significant anti-fatigue function in mice.