A new crown ether of 2,13-dibenzothiazol-2'-yldibenzo[b,k]-18-crown-6 was synthesized from 2,13-diformyldibenzo[b,k]-18-crown-6 with 2-aminothiophenol.The binding behavior and the optical properties of the crown ether were examined through UV-visible spectroscopy and fluorescence spectroscopy.When complexed with Na+,K+,Rb+ and Cs+ ions,it led to intramolecular charge transfer and caused the changes of the fluorescence spectra.The protonation of the crown ether was also studied.