In　thermal　power　plant,　the　measurement　of　unburned　carbon　in　fly　ash　becomes　increasingly　important　because　unburned　carbon　contents　are　usually　important　factors　for　the　operation　of　power　plants　and　it　can　be　an　indicator　of　the　combustion　conditions　Thus,　the　goal　of　combustion　optimization　and　efficiency　improvement　can　be　achieved.　More　specifically,　the　unburned　carbon　concentration　in　fly　ash　reflects　the　combustion　efficiency　of　the　power　generator　set.　The　combustion　efficiency　decreases　with　increasing　of　unburned　carbon　level　in　fly　ash,　which　means　a　loss　of　fuel　energy.　Owing　to　the　non-contact,　fast　response,　high　sensitivity　and　online　measurement　features,　LIES　was　used　to　measure　the　quantitative　contents　in　fly　ash　in　this　research.　But　the　carbon　emission　intensity　changed　with　the　fluctuant　amount　of　CO2　in　flue　gas.　In　this　study,　dual-channel　spectrometer　was　utilized　to　analyze　the　elemental　spectra　of　C,　Si,　Mg,　Fe,　Ca,　Al　and　so　on,　and　the　neighboring　elemental　spectra,　such　as　C　and　Fe,　can　be　recognized　in　the　high　resolution　channel,　which　means　sufficient　fly　ash　spectrum　information　can　be　gained　with　enough　measurement　accuracy　at　the　same　time.　Cyclone　was　designed　and　two-stage　cyclone　system　was　proposed　into　the　system　of　LIBS　measurement　for　unburned　carbon　contents　in　fly　ash.　Fly　ash　particles　from　the　feeder　flow　through　the　two-stage　cyclone　and　went　into　the　chamber.　The　laser　shot　on　the　fly　ash　through　the　lens　Plasma　was　acquired　and　then　recorded　and　analyzed　by　spectrometer　and　ICCD　camera.　The　two-stage　cyclone　system　was　proven　to　be　detectable　for　the　unburned　carbon　in　fly　ash.　In　addition,　two-stage　cyclone　system　can　be　able　to　separate　and　collect　fly　ash　particles　from　flow　gas　to　reduce　the　influence　of　CO2　in　fly　ash　particle　flow,　thus,　exact　data　can　be　got　to　guide　the　operation　of　the　thermal　power　plant,　which　provide　more　benefits　to　the　engineering　applications　of　LIES.