As　a　main　pollution　gas,　the　emission　of　NO2　is　endangering　to　the　environment　and　human　health,　which　should　be　monitored　to　achieve　better　governance.　The　existing　imaging　detection　methods　possess　the　advantages　of　a　wide　application　range　and　good　real-time　performance,　while　accuracy　and　applicability　are　concerned　in　the　reconstruction　background.　A　method　for　quantitatively　monitoring　gas　concentration　using　images　of　dual-channel　target　gas　is　proposed　in　this　study.　The　NO2　concentration　is　retrieved　from　the　ratio　of　405　and　470　nm　dual-channel　light　intensity,　and　the　following　theoretical　and　experimental　research　is　carried　out.　Specifically,　the　relationship　between　gas　column　concentration　and　dual-channel　light　intensity　ratio　is　obtained　according　to　theoretical　derivation.　The　effect　of　the　dual-channel　exposure　time　on　the　calibration　equation　is　analyzed.　The　collected　dual-channel　light　intensity　ratio　is　compared　with　the　theoretical　value,　and　the　difference　between　them　is　0.26%.　The　optimal　value　of　dual-channel　light　intensity　ratio　under　different　solar　zenith　angles　is　measured　by　collecting　the　solar　scattered　radiation　spectra　at　26.08°　north　latitude　under　various　meteorological　conditions.　The　performance　of　the　detection　camera　is　analyzed,　and　the　detection　range　is　19.6　ppm　m.　Concentration　calibration　and　retrieval　experiments　give　a　calibration　function,　retrieve　the　two-dimensional　distribution　of　gas　concentration　in　diffusion,　and　validate　the　reliability　of　the　dual-channel　spectral　imaging　method　for　quantitative　detection　of　gas　concentration.　©　2022,　Science　Press.　All　right　reserved.