A new composite photocatalyst Ag/AgCl/ZnO was fabricated by a two-step synthesis method under the hydrothermal condition. The sample was characterized by XRD, TG-DSC, SEM, TEM, DRS and XPS. The results showed that the samples were composed of Ag, AgCl and ZnO, and the particle size was in the range of 100nm–1μm. Methyl orange (MO) was used as a representative dye pollutant to evaluate the photocatalytic activity of Ag/AgCl/ZnO. The photocatalytic activity of Ag/AgCl/ZnO catalyst was higher than that of the pure ZnO catalyst. It was found that the Ag/AgCl/ZnO structure changed to Ag/ZnO gradually after several repeated experiments. However, the photocatalytic ability of the sample was not reduced. Finally, a possible photocatalytic mechanism was proposed.