Provided are a Bifidobacterium longum BL16 having cephalosporin resistance and high expression of Sir2 protein, and application thereof in preparing foods or medicines for anti-aging, enhancing immune function, or regulating intestinal microbiota. The Bifidobacterium longum BL16 having cephalosporin resistance and high expression of Sir2 protein improves the micro-ecological environment of the intestinal tract, removes free radicals from the body, delaying the process of aging of animals, and can also significantly increase the weight of aging organs, maintain the immune function of an organism, and improve disease resistance capability; Therefore the Bifidobacterium longum BL16 having cephalosporin resistance and high expression of Sir2 protein can be used for preparing foods or medicines for anti-aging, enhancing immune function, or regulating intestinal microbiota.
