Mn-doped ZnS nanopatricles synthesized by solvothermal method weresuccessfully coated with SiO2 shells of various thicknesses by hydrolysisreaction of tetraethyl orthosilicate (TEOS). The samples were characterized by X-ray diffraction(XRD), transmission electron microscopy images (TEM), X-rayphotoelectron spectroscopy (XPS) and the room temperature photoluminescence (PL)spectra. When the ZnS∶Mn nanoparticles were coated with SiO2 shells, an obviousincrease in particle size and a clear shell of SiO2 can be observed. The XPSmeasurement also gave the evidence for the core/shell structure of ZnS∶Mn/SiO2nanoparticles. Because the surface modification effect and the decrease inluminescent centers effect are concurrent in the SiO2 shells, the Mn emissionintensity first increased and then decreased with the thickening of the SiO2shell. The intensity, which attained its maxium at 5 shell thickness, was as 7times as that for the bare ZnS∶Mn nanoparticles.(2006BS04034)和2008年教育部新世纪优秀人才支持计划项目(NCET-08-0511)资助