Ag supported ZnS (ZnS/Ag) composite nanowires were prepared by a hydrothermal method. The phase structure, morphology and optical properties of the prepared nanowires were characterized by XRD, TEM and UV-Vis spectrophotometer. With methyl orange as degradation target, photocatalytic performances of the prepared composite nanowires under ultraviolet radiation were evaluated. Results show that the photocatalytic activity of ZnS nanowires prepared by the hydrothermal method was superior to that of commercial ZnS. Meanwhile, the Ag supported ZnS nanowires exhibit higher photocatalytic activity than that of non-supported ZnS nanowires, which is attributed to that Ag particles promote the separation of the pairs of excited electrons and holes, and increase the activity points of ZnS nanowires