Indole croconium dye was obtained by the condensation reaction between 2,3,3-trimethylindolenine and croconic acid prepared using copper oxide as a catalyst．The binding properities of the receptors with cations such as，Na 、K 、Mg2 、Ca2 、Ni2 、Mn2 、Zn2 、Ag and Ba2 were investigated by UV-Vis spectroscopy．The results showed that the absorbance obviously decreased upon the addition of Ag to ICR ethanol/water (4:1，V/V)．Moreover，a clear color from olive green to orange．Meanwhile，the fluorescence spectra of ICR ethanol/water (4:1，V/V) were investigated with adding increasing concentration of Ag ion．It was found that the fluorescence strength of ICR ethanol/water (4:1，V/V) was quenched．The results indicated that ICR exhibited high selective and sensitive recognition towards Ag ．The cyclic voltammetry and 1H NMR were also used for the recognition study of ICR to transition metal ions．