A　novel,　highly　sensitive　and　selective　dual-readout　sensor　(colorimetric　and　fluorometric)　for　the　detection　of　lysozyme　was　proposed.　The　fluorescence　of　triazolylcoumarin　molecules　was　quenched　by　Au　nanoparticles　(AuNPs)　initially　through　the　fluorescence　resonance　energy　transfer　(FRET),　after　the　addition　of　lysozyme,　the　stronger　binding　of　lysozyme　onto　the　surfaces　of　AuNPs　made　triazolylcoumarin　molecules　remove　from　the　AuNPs　surface　and　led　to　the　recovery　of　the　fluorescence　of　triazolylcoumarin　molecules,　and　accompanied　by　the　discernable　color　change　of　the　solution　from　red　to　purple.　The　lowest　detectable　concentration　for　lysozyme　was　50　ng　mL-1　by　the　naked　eye,　and　the　limit　of　detection　(LOD)　was　23　ng　mL-1　by　fluorescence　measurements.　In　addition,　satisfactory　results　for　lysozyme　detection　in　hen　egg　white　were　confirmed　in　the　study.　Moreover,　the　presented　sensor　provides　a　reliable　option　to　determine　lysozyme　with　high　sensitivity　and　selectivity.　©　2013　The　Royal　Society　of　Chemistry.