Abstract: Objective: To investigate the antioxidant effect of Rhodiola rosca oligomeric proantho cyanidns ( OPCRR) in the aged mice induced by D-galactoseactose.Method: Via the process of establishing oxidative damage model by hypodermic injection of D- galactose, OPCRR of different doses ( high dose: 320mg /kg·bw、middle dose: 160mg /kg·bw、low dose: 80 mg /kg·bw) were orally given to mice at the same time for consecutive 49d.The level of SOD, GSH-Px, MDA in mouse serum and organs, and senescent-related enzyme ( MAO) in mouse brain and liver were investigated in peroxide damaged mice in the experiment of the antioxidant activity in vivo.Results: Compared with model control group, a dose of OPCRR could significantly increase SOD, GSH-Px activity of serum, heart, liver and brain, and significantly decrease MDA level, while highest dose had superior effert; high dose group had increased SOD level of serum, heart, liver and brain by 29.5%, 29.5%, 62.7% and 90.8%, while GSH-Px activity had increased 67.8%, 58.4%, 32.1% and 50.3%, and the MDA content was decreased by 19.2%, 30.0%, 33.3% and19.2%. In addition, the middle and high dose group significantly decreased MAO activity of brain ( p < 0.01) by22.3% and 28.6%; High dose group was significantly decreased MAO level of liver ( p < 0.05) by 36.5%.Conclusion:OPCRR's effect on antagonizing D- galactoseactose- induced peroxidative damage was confirmed, and had a degree of ability of preventing oxidation and senescence.