In　this　work,　3,3＇,　5,5＇-tetramethylbenzidine(II)　(TMB2+),　derived　from　H2O2-horseradish　peroxidase　(HRP)-3,3＇,　5,5＇-tetramethylbenzidine　(H2O2-HRP-TMB)　reaction　system,　was　used　to　etch　AuNRs　to　generate　different　colors　of　solution.　Many　enzyme　reactions　are　involved　in　the　production　of　H2O2　(e.g.,　glucose　can　react　with　the　dissolved　oxygen　in　the　presence　of　glucose　oxidase　(GOx)　to　produce　H2O2).　Given　this　information,　a　simple　visual　biosensor　was　developed　in　this　study,　with　glucose　as　the　example　target.　The　detection　range　of　the　proposed　system　varied　with　the　experimental　conditions,　such　as　the　concentration　of　GOx　and　HRP,　and　enzymatic　reaction　time.　Under　the　optimized　conditions,　the　longitudinal　shift　of　localized　surface　plasmon　resonances　(LSPR)　had　a　linear　correlation　with　the　glucose　concentration　in　the　range　of　0.1　similar　to　1.0　mM.　Meanwhile,　the　solution　displayed　a　specific　color　in　response　to　the　glucose　concentration,　thus　enabling　the　visual　quantitative　detection　of　glucose　at　a　glance.　Compared　with　the　traditional　monochromic　colorimetry,　this　multicolor　glucose　sensor　generates　various　vivid　colors,　which　can　be　easily　distinguished　by　naked　eyes　without　any　sophisticated　instrument.　Notably,　the　proposed　method　has　been　successfully　applied　to　detect　glucose　in　serum　samples　with　satisfied　results.