The spectral properties of a cyanine dye in the system of reverse micelles and the effect of ω of reverse micelles on the fluorescence spectral of this cyanine dye are studied. The adsorption state and the formation of J-aggregate of the cyanine dye adsorbed on AgCl nanoparticles with different diameters are also discussed. The cage effects of the water pool of reverse micelles on the quantum yield of fluorescence and the formation of J-aggregate of the dye are investigated, specially.