Two　novel　carborane-based　benzimidazolium　fluorescent　probes　4a　and　4b　were　synthesized　using　1,2-bis(4-benzylbromophenyl)-o-carborane　as　starting　materials.　The　structures　were　characterized　by　IR,　H-1　NMR,　C-13　NMR,　B-11　NMR　and　ESI-MS,　and　the　recognition　properties　of　probes　4a　and　4b　for　nucleotides　were　studied　by　fluorescence　and　ultraviolet　spectroscopy.　The　results　of　fluorescence　titration　showed　that　probes　4a　and　4b　could　achieve　on-off　response　to　uridine　monophosphate　(UMP),　and　had　good　selectivity　and　sensitivity.　The　detection　limit　of　probe　4b　for　UMP　could　reach　3.41　x　10(-8)　mol/L.　The　recognition　mechanism　of　the　probe　4b　was　studied　by　Job　＇s　curve　and　(HNMR)-H-1　titration.