We discuss studies aimed to promote a healthy aging process, prevent health problems related to aging, correctly understand the aging mechanism, and develop effective anti-aging treatment measures. Systemic injection of D-galactose has been used for artificial induction of aging in vitro and in vivo, and anti-aging research. This review summarizes the characteristic changes of aging induced by D-galactose from four aspects: oxidative stress, mitochondrial dysfunction, immune aging, and the influence of immune aging on various organs. Furthermore, a theoretical basis for antiaging is provided from various viewpoints.