The　detection　of　trypsin　is　significantly　important　for　both　clinical　diagnosis　and　disease　treatment.　In　this　study,　an　innovative　multicolor　sensor　for　trypsin　detection　has　been　established　based　on　the　regulation　of　the　peroxidase　activity　of　bovine　serum　albumin-coated　gold　nanoclusters　(BSA-Au　NCs)　and　efficient　etching　of　gold　nanobipyramids　(Au　NBPs).　BSA-Au　NCs　have　slight　peroxidase　enzyme　activity　and　can　catalyze　the　oxidation　of　3,3′,5,5′-tetramethylbenzidine　(TMB)　to　generate　TMB+,　while　trypsin　can　hydrolyze　BSA　ligands　on　the　surface　of　BSA-Au　NCs,　thus　exposing　more　catalytic　active　sites　of　BSA-Au　NCs　and　resulting　in　the　enhancement　of　the　peroxidase　activity　of　BSA-Au　NCs,　hence　more　TMB+　is　generated.　Under　acidic　conditions,　TMB+　can　etch　Au　NBPs　efficiently,　consequently　affecting　the　aspect　ratio　of　Au　NBPs　accompanied　by　the　ultraviolet-visible　(UV-vis)　spectra　blue　shifting　of　the　system.　Furthermore,　this　also　results　in　color　variations　that　can　be　distinguished　and　recognized　by　naked　eyes　without　any　expensive　and　sophisticated　instruments.　This　multicolor　sensor　has　an　available　linear　relationship　with　the　logarithm　of　the　trypsin　concentration　in　the　range　of　0.1-100　μg/mL,　and　the　detection　limit　is　0.045　μg/mL.　The　designed　sensor　has　been　used　to　detect　the　concentration　of　trypsin　in　human　serum　samples　from　healthy　individuals　and　pancreatitis　patients　with　satisfactory　results.　©　2023　American　Chemical　Society.