Development　of　convenient　but　sensitive　method　for　influenza　detection　is　highly　important　in　immediate　and　effective　clinical　treatment.　In　this　study,　an　ultrasensitive　colorimetric　approach　combining　the　advantages　of　the　convenience　of　the　enzyme-induced　metallization　and　the　high　specificity　of　enzyme-linked　immunosorbent　assay　for　the　detection　of　influenza　virus　A　(H7N9　as　model)　has　been　developed.　Two　rounds　of　amplification　are　utilized　to　enhance　the　detection　sensitivity.　The　amplification　of　enzymatic　reaction　combines　with　the　specific　optical　properties　of　gold　nanoparticles　causing　the　enhancing　of　the　optical　signal　immensely.　In　addition,　the　increased　surface　area　and　the　magnetic　enrichment　effect　also　enable　the　magnetic　bead　(MB)　to　catch　a　large　number　of　alkaline　phosphatase　(ALP)　and　detection　antibody　(Ab(2)),　thus　very　small　amounts　of　the　virus　can　be　easily　detected.　Compared　with　conventional　method,　this　approach　exhibits　outstanding　sensitivity　for　ALP　detection,　0.2　U/L　of　ALP　can　be　distinguished　with　a　spectrometer　and　2　U/L　with　the　naked　eye.　And　as　low　as　25　pg/mL　of　H7N9　can　be　detected　by　the　naked　eye.　This　approach　shows　an　extensive　horizon　for　bioassays　and　is　available　in　clinical　diagnosis　with　the　advances　of　simplification,　effectiveness,　low　cost　and　sensitive　readout.　(C)　2016　Elsevier　B.V.　All　rights　reserved.