Ag+-doped　ZnS　nanocrystals　surface-capped　with　thiourea　(expressed　as　ZnS:Ag/thiourea)　were　synthesized　through　sol-gel　method　with　thiourea　as　a　surface　modifier　and　characterized　by　X-ray　diffraction　(XRD),　transmission　electron　microscope　(TEM),　X-ray　fluorescence　spectrum　(XRF),　infrared　spectrum　(IR),　UV-Vis　absorption　spectrum　(UV-Vis),　and　photoluminescence　spectrum　(PL).　The　results　show　that　Ag+　ions　are　doped　in　ZnS　nanocrystals,　and　the　sulfur　atoms　in　thiourea　molecules　coordinate　with　metal　ions　on　the　surface　of　the　nanocrystals.　The　spherical　ZnS:Ag/thiourea　nanocrystals　with　an　average　diameter　of　5　nm　have　good　fluorescent　characteristics,　and　therefore　have　great　potential　for　use　in　molecular　assembly　and　novel　luminescence　materials.