Ag/AgCl nanoparticles were synthesized in situ under 395 nm UV light with Cl- in reverse osmosis water (RO) and AgNO3 as raw materials. The morphology and size distribution of the samples were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS).The crystal structure, element valence and photocatalytic performance of the composite were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible absorption spectra (UV-Vis) and fluorescence spectra separately. The results show that the Ag/AgCl composite are spherical particles with an average size of 100 nm. At the same time, the formation process of composite nanoparticles can effectively degrade rhodamine 6G. The degradation rate and quenching rate of rhodamine 6G can reach 96.5% and 95% when the silver ion solution was irradiated 3 min.