Hydrogen　sulfide　(H2S)　is　an　active　physiological　molecule,　and　its　intracellular　level　has　great　significance　to　life　functions.　In　this　study,　an　effective　and　sensitive　method　was　developed　for　H2S　sensing　with　dark　field　microscopy　(DFM).　The　proposed　method　employed　AuNPs　as　the　signal　source,　DFM　as　the　readout　system,　and　an　intelligence　algorithm　as　the　image　processing　and　output　systems,　respectively.　The　AuNP　surface　was　modified　with　azido　and　alkynyl　in　advance,　and　then　added　into　a　tube　cap.　As　the　H2S　evaporated　from　the　solution　and　selectively　reduced　azido　to　amino,　the　click　chemistry　reaction　was　inhibited,　which　resulted　in　the　AuNPs　being　well　dispersed　in　the　solution;　otherwise,　AuNP　aggregation　occurred.　The　scattering　colour　of　single　AuNPs　could　be　easily　distinguished　from　that　of　AuNP　aggregations　with　DFM,　and　the　number　or　ratio　of　single　AuNPs　could　also　be　easily　obtained　by　the　custom　algorithm.　The　results　showed　that　the　H2S　content　could　be　linearly　analyzed　in　a　range　from　2-80　μM.　Furthermore,　the　proposed　sensing　strategy　has　been　applied　for　H2S　detection　in　cell　lysate.　Compared　with　the　traditional　colorimetric　method,　the　results　showed　no　significant　difference,　indicating　the　good　prospects　of　the　algorithm　and　proposed　H2S　sensing　method.　©　2022　The　Royal　Society　of　Chemistry