In order to study the effects of weaning ages on antioxidant capacities, total 24 piglets were randomly assigned to four treatments, with six replicates in each treatment witheach piglet asa replicate. Piglets from different treatment groups were weaned at 14, 21, 28 and 35 ages, respectively, and slaughtered at the age of 42days, blood and tissue samples of liver, kidney and lung tissue were obtained. Contents of Malondialdehyde (MDA) and activities of total superoxide dismutase (T-SOD), Glutathione peroxidase (GSH-Px) andcatalase (CAT) were determined. The results showed that plasma MDA levels ofpiglets weaned at 21, 28 and 35 days were significantly lower than those weaned at the age of 14 days (P<0.05). With the weaning age postponed, plasma T-SOD and GSH-Px activities in piglets increased gradually, where T-SOD and GSH-Px activities of piglets weaned at 28 and 35 days were significantly higher than those weaned at 14 days (P<0.05).Tissue MDA contents were affected by the weaning age, where liver(P<0.05), kidney(P<0.05) and lung(P<0.05) MDA contents weaned at 35 days were decreased in comparison with those weaned at 14 ages, respectively. The T-SOD and GSH-Px activities in the liver, kidney and lung tissues gradually increased with the delayed weaning ages. Activities of T-SOD (P<0.05) and GSH-Px(P<0.05) were higher in tissues of the piglets weaned at 35 ages than those weaned at 14 ages (P< 0.05). The CAT activities did not show significant differences in blood and tissues of liver, kidney and lung among each weaning groups. Those results indicated that the antioxidant function was markedly affected by weaning ages in piglets, and early weaning could decrease antioxidant capacity in piglets.