The two naturally occurring isotopes of lithium, Li-6 and Li-7, have important roles in the nuclear energy industry. Among many techniques for the separation of lithium isotopes, high isotope separation factors are usually realized with the polydentate complex method. Crown ethers, for their selective-complexing ability with metal cations, have been regarded as perhaps the most effective extractants. for lithium isotope separation. This review summarizes the application of crown ether and crown ether chelating resin for lithium isotope separation based on polydentate complexing method, exemplify recent developments in complexation of metal-containing crown ethers with metal cations, and prospect their potential in separation of lithium isotopes.