Astrocytes are fundamental for homoeostasis, defence and regeneration of the central nervous system. Loss of astroglial function and decrease of astroglial reactivity lead to the physical aging of brain and incidence of neurodegenerative diseases. Astrocytes play an important role in cerebral aging and in the pathophysiogenesis of Alzheimer’s disease (AD), and also take part in the energy metabolism in the brain. Medication can regulate the morphology and functions of astrocytes, suggesting that astrocytes can be regarded as a target for the treatment of AD. In this article, we reviewed the roles of astrocytes in the physiological aging and the pathogenesis of AD.