Herein　we　designed　a　selective　and　smartphone-based　strategy　for　visual　detection　of　alkaline　phosphatase　(ALP)　by　utilizing　the　property　of　amino-functionalized　copper　(II)-based　metal-organic　frameworks　(NH2-Cu-MOFs)　with　oxidase　mimic　property　and　fluorescence　property.　Surprisingly,　the　oxidase　mimic　property　of　NH2-Cu-MOFs　can　work　well　at　a　high　pH　value　8.0.　Thus,　a　cascade　reaction　between　ALP　and　NH2-Cu-MOFs　was　realized　for　the　construction　of　a　ratiometric　multicolor　sensing　platform　through　the　controllable　catalytic　activity　of　NH2-Cu-MOFs　by　pyrophosphate　(PPi)　and　ALP.　The　catalytic　activity　of　NH2-Cu-MOFs　was　greatly　inhibited　because　of　the　binding　ability　of　Cu2+　with　PPi.　When　the　ALP　was　added,　the　catalytic　activity　of　NH2-Cu-MOFs　was　restored　and　then　further　catalyzed　the　o-phenylenediamine　to　form　the　2,　3-diaminophenazine　due　to　the　hydrolysis　function　of　ALP　towards　PPi　into　orthophosphates.　RGB　analysis　of　the　fluorescent　sample　images　was　adopted　for　ALP　quantitative　analysis.　Besides,　a　hydrogel　test　kit　and　mobile　app　for　ALP　detection　were　designed　as　conceptual　products　for　point-of-care.　The　LODs　of　the　fluorescence　sensing　platform　was　0.078　mU　mL−1　and　0.35　mU　mL−1　by　solution　analysis　and　hydrogel　test　kit　analysis,　respectively.　This　fluorescent　visual　method　was　applied　to　ALP　detection　in　serum　samples　with　satisfying　results,　which　opened　a　promising　horizon　for　the　diagnosis　of　other　biomarkers　in　clinical　serum　samples　based　on　ALP-mediated　enzyme-linked　immunosorbent　assay　for　the　development　of　biomedicine　and　clinical　diagnosis.　©　2019　Elsevier　B.V.