A　dual-readout　immunoassay　based　on　QDs-FM@ALP-SA　and　click　chemistry　was　developed　for　quick　and　sensitive　detection　of　norfloxacin　(NOR),　which　is　an　important　fluoroquinolone　antibiotic.　In　the　system,　the　NOR-biotin　conjugate　(NOR-Biotin)　was　synthesized　by　click　chemistry　for　signal　transformation,　and　alkaline　phosphatase–labeled　streptavidin　(ALP-SA)　was　attached　to　quantum　dot　fluorescence　microspheres　(QDs-FM)　by　an　activated　ester　method　to　form　QDs-FM@ALP-SA　for　signal　amplification.　Here,　QDs-FM　was　a　dual-functional　carrier:　it　was　used　not　only　as　a　chemiluminescence　signal　amplification　carrier　but　also　as　a　fluorescent　signal　due　to　its　fluorescence　character.　The　NOR　antibody　was　coated　on　a　96-well　chemiluminescence　microtiter　plate,　and　NOR-Biotin　was　bound　to　the　antibody　specifically.　Then,　QDs-FM@ALP-SA　was　combined　with　NOR-Biotin　to　develop　a　direct　competition　chemiluminescence/fluorescence　immunoassay　(dc-CLIA/FIA).　The　IC50　values　were　0.345　and　1.206　ng/mL　for　dc-CLIA/FIA,　respectively.　The　linear　range　was　0.013–12.48　ng/mL　and　0.042–39.86　ng/mL,　respectively.　The　recovery　from　the　standard　fortified　blank　milk　samples　was　in　the　range　of　86.44%–101.3%.　Therefore,　this　method　could　be　a　useful　tool　for　routine　screening　of　NOR　residues　in　milk.　©　2021　Elsevier　B.V.