CdS　nanoparticles　were　successfully　coated　on　multi-walled　carbon　nanotubes　(MWNTs)　via　electron　beam　irradiation　in　the　water　system.　The　resulting　products　were　analyzed　by　XRD,　FT-IR,　UV-vis,　TEM　and　AFM　all　kinds　of　characterization　techniques.　The　results　showed　that　cadmium　cations　were　introduced　to　the　surface　of　MWNTs　through　ion　exchange,　and　by　chemical　reaction　between　cadmium　cations　on　the　carbon　nanotubes　and　sodium　thiosulfate　pentahydrate　under　electron　beam　irradiation,　cadmium　sulfide　nanoparticles　were　densely　deposited　on　carbon　nanotubes.