ZnS nanoparticles with Mn2+ doping (0–2.5%) were prepared through a simple chemical method. The nanostructures of the prepared undoped ZnS and Mn2+-doped ZnS:Mn nanoparticles had been characterized by X-ray power diffraction (XRD), energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), photoluminescence spectra (PL) and UV–vis absorption spectra. The mean size of the particles was found to be approximately 3-5 nm through XRD measurements, TEM and the UV–vis absorption spectra. It was found that the Mn2+ 4T1→6A1 emission intensity of ZnS:Mn nanoparticles was significantly enhanced with the increase of Mn2+ concentration, which arrived a maximum value when Mn2+ initial doping concentration was 1.5%. Continue increasing the Mn2+ concentration, namely more than 1.5%, the Mn2+ 4T1→6A1 emission intensity became weakened. And the resultant ZnS:Mn nanoparticles exhibited high efficiency for degrading methylene blue under UV light irradiation.