For the impact of oxidative stress on animal husbandry industry,this study aimed to investigate the antioxidant property of Enterococcus faecium HDRsEf1,which would provide a new method for development of new biological antioxidants.To assess antioxidant activity of the strain in vitro,the resistance to hydrogen peroxide,scavenging activity of the free radical (DPPH free radical,hydroxyl radical and superoxide radical),and reducing activity were analyzed.And to evaluate the antioxidant property of the E. faecium HDRsEf1 in vivo,the D-galactose induced aging model were built.The results showed that the strain could survive under 2.0 mmol/L of hydrogen peroxide.The fermentation broth of HDRsEf1 not only had good scavenging activity of the DPPH free radical but also had a strong reducing activity.The intact cell,cell-free extract,fermentation broth of E. faecium HDRsEf1 also displayed good scavenging activity of hydroxyl radical,but weak superoxide radical.The experimental investigation demonstrated that the cell and fermentation broth of E. faecium HDRsEf1 displayed effective function of antioxidation and antiaging by increasing the activities of superoxide dismutase (SOD) and decreasing the malondialdehyde (MDA) level prominently in the D-galaetose treated mice.Therefore,E. faecium HDRsEf1 had good antioxidant activity in vitro and in vivo.