In this paper, the anti-aging effect of polysaccharides extracted from Athyrium multidentatum (Doll.) Ching (PA) was investigated on aged mice induced by D-galactose. After administration of PA for 40 days, SOD, CAT and GSH-Px activities in PA groups was significantly enhanced and MDA level was decreased compared with aged group. There were significant differences between PA high dosage group and aged group (P < 0.05). SOD activity in PA high dosage group was 123.7 ± 12.5 U/mL, which was stronger than VE group and similar to normal group. The antioxidative enzyme activities in mice were increased in dose-dependent patterns. These results demonstrated that PA could remarkably augment the activities of antioxidative enzymes and lessen the product of lipid peroxide, which might provide an explicit interpretation to the anti-aging mechanism of PA.