MC-LR　possessing　strong　hepatotoxicity,　potential　carcinogenicity,　and　biological　toxicity　could　have　an　intensive　influence　on　human　health　and　the　aquatic　ecological　environment　and　need　to　be　monitored　critically.　For　the　specific　and　highly　sensitive　analysis　performance,　agold-magnetic　composite　nanoparticlemodified　by　aptamer-cDNAfluorescent　hybridization　probe　(Fe3O4　@MIL-101-NHz@Au@aptamer)　was　prepared　and　applied　for　sensing　detection　of　MC-LR　in　water　with　laser-induced　fluorescence　(LIF).　This　work　studied　the　feasibility,　optimization　of　analysis　conditions,　specificity,　stability　of　the　method,　and　sample　analysis　application.　As　a　result,　a　high　Brunauer-Emmett-Teller　(BET)specific　surface　area　of　114.　02　m＂:　g-1　was　achieved　in　Fe3O4　@MIL-101-NH2　@　AuNPs,　which　resulted　in　a　high　modification　rate　of　up　to　98.　8%　achieved　for　aptamer-cDNA　fluorescenthybridization　probe.　With　the　excitation　wavelength　of　497　nm,　the　aptamer-cDNA　fluorescent　probe　has　a　strong　fluorescence　response　with　the　emission　wavelength　of　512　nm　to　the　trace　MC-LR.　Under　the　optimal　conditions　(pH7.　5,　NaCl　concentration　500　mmol:　L_1,　nanogold　size　20　nm,　analytical　time　30　min),　a　good　linear　relationship　between　MC-LR　concentration　and　fluorescence　intensity　was　achieved　in　a　wide　linear　range　(0.　020　3.　000　fig:　L_1)　with　the　limit　of　detection　(LOD)　as　low　as　0.　006　fig:　L_1,　which　was　1.　6　22.　3　folds　better　than　that　of　the　most　fluorescence　methods　reported　previously.　The　relative　standard　deviation　(RSD)　of　intra-day,　intra-day,　and　inter-batch　was　gained　in　1.7%　8.　8%,　and　the　relative　error　(RE)　of　4.　3%　4.　1%.　High　specific　selectivity　and　low　cross-reactivity　for　MC-LR　(1.　0　jug:　L_1)　were　also　achieved　using　theas-prepared　fluorescent　probe,　even　if　the　concentration　of　interfering　toxins　(MC-RR,　MC-YR,　OA)　was　100　folds　higher　than　that　of　MC-LR.　The　fluorescence　responses　of　MC-LR　in　these　mixtures　werewell　consistent　with　that　of　MC-LR　in　the　standard　solution.　Applied　to　the　analysis　of　samples　from　the　Minjiang　River,　Lake　Water,　and　the　inland　river,　the　identification　of　MC-LR　in　water　samples　was　satisfactory.　The　recovery　yields　of　MC-LR　for　three　concentrations　(0.050,　0.　100　and　1.　000,xg:　L＂1)　rangedin　(90.　1　%　+　6.　4%)　~　(104.　2%　+　7.　0%)　(=3).　The　results　were　consistent　with　those　obtained　by　the　LC-MS　method　[(91.　3%+　7.　0%)~　(104.　4%+　2.　0%),　n　=　3].　It　might　light　a　new　technique　for　the　specific　and　rapid　monitoring　technology　for　tracing　MC-LR　in　the　environmental　water.　©　2023　Science　Press.　All　rights　reserved.