Abstract： Photoaging is the superposition of chronic solar ultraviolet (UV) irradiation-induced damage and accounts for most age-associated changes in skin appearance.The molecular mechanisms of photoaging are triggered by reactive oxygen species (ROS) produced by skin cells after UV irradiation,which subsequently activate cell surface receptors,initiate intracellular signalling cascades,stimulate transcription factor activator proteins and nuclear factor-kappa B,and finally induce the degradation of skin extracellular matrix (ECM) and initiation of inflammation.Estrogen induces collagen synthesis,increases skin water content and improves the appearance and functions of photoaged skin by interfering with the transforming growth factor (TGF)-β/Smad signaling pathway,and finally prevents photoaging etiologically.Different tissues express different estrogen receptors (ER),and skin mainly expresses ER-β.When binding with the ligand,ER-β does not carry the breast and uterine proliferation liabilities of ER-α,therefore,to develop and utilize selective estrogen receptor activators may be of great value to the prevention and control of photoaging.