Herein,　a　novel　and　facile　method　for　preparing　highly　water-soluble　CdS　nan　oparticles　has　been　developed.　Cadmium　acetate　dehydrate　was　mixed　in　thiourea　solution,　using　ethylenediaminetetraacetic　acid　(EDTA)　as　complexing　agent.　Electronic　accelerator　was　used　as　radiation　source.　CdS　nanoparticles　were　prepared　rapidly　at　room　temperature　under　atmospheric　pressure　without　any　kind　of　toxic　reagents.　Unlike　those　traditional　routes,　this　method　is　facile　and　green,　free　of　high　temperature　and　toxic　reagent.　The　prepared　CdS　nanoparticles　had　an　average　diameter　about　3nm.　The　product　showed　quantum　confinement　fluorescing　in　the　blue　region　and　dispersed　in　water　well,　which　make　it　potentially　using　as　fluorescent　biomarkers.　Meantime,　the　prepared　CdS　nanoparticles　showed　the　photocatalytic　activity　to　degrade　organic　pollutant.