Fluorescence　immunochromatographic　assay　(FICA)　is　a　rapid　immunoassay　technique　that　has　the　characteristics　of　high　precision　and　sensitivity.　Although　image　FICA　strip　readers　have　the　advantages　of　high　portability　and　easy　operation,　the　use　of　high-precision　complementary　metal　oxide　semiconductor　(CMOS)　image　sensors　leads　to　an　increase　in　overall　cost.　Considering　the　popularity　of　CMOS　image　sensors　in　smartphones　and　their　powerful　processing　functions,　this　work　developed　a　smartphone-based　FICA　strip　reader.　An　optical　module　suitable　for　the　test　strips　with　different　fluorescent　markers　was　designed　by　replacing　the　excitation　light　source　and　the　light　filter.　An　android　smartphone　was　used　for　image　acquisition　and　image　denoising.　Then,　the　test　and　control　lines　of　the　test　strip　image　were　recognized　by　the　sliding　window　algorithm.　Finally,　the　characteristic　value　of　the　strip　image　was　calculated.　A　linear　detection　range　from　10　to　5000　mIU/mL　(R2　=　0.95)　was　obtained　for　human　chorionic　gonadotrophin　with　the　maximum　relative　error　less　than　9.41%,　and　a　linear　detection　range　from　5　to　4000　pg/mL　(R2　=　0.99)　was　obtained　for　aflatoxin　B1,　with　the　maximum　relative　error　less　than　12.71%.　Therefore,　the　smartphone-based　FICA　strip　reader　had　high　portability,　versatility,　and　accuracy.　©　2020,　MDPI　AG.　All　rights　reserved.