Abstract: Lithium is composed of two stable isotopes that both have important application in the nuclear power industry. The industrial method for lithium isotope separation is with amalgam, but huge volumes of toxic mercury used in this method bring about serious health and environmental problems. Thus, it is imperative to look for a green and effective method for lithium isotope separation. Since the crown ether was synthesized, it has become a research focus for its excellent properties on lithium isotope separation. In this paper, to provide a reference for the further research, nearly 40 years of research achievements in lithium isotopes separation by crown compounds were classified and summarized.