Nanocrystalline ZnS∶Mn contained SiO2 aerogels were prepared by sol-gel process. The sizes of the nanocrystals were estimated by X-ray diffraction and caculated from the emission spectra of the aerogels. The excitation, emission and time-resolved spectra of the aerogels were investigated. Experiments show high luminescence efficiency and short decay time of Mn2+ in nanocrystalline ZnS. The decay time is one order magnitude less than that in bulk ZnS crystal.