Selective　non-catalytic　reduction　(SNCR)　is　a　denitration　method　in　the　high　temperature　area,　and　NH3　or　urea　is　used　for　SNCR　as　reducing　agents　to　react　with　NOX　to　produce　N2　in　the　flue　gas　in　the　temperature　ranged　from　850°C　to　1100°C.　The　SNCR　deNOx　technology　has　been　well　used　in　utility　boiler,　but　compared　with　it,　the　lower　denitration　efficiency　and　the　larger　consumption　of　ammonia　indicate　a　more　complex　process　in　cement　pre-calciner.　Unlike　in　utility　boiler,　the　presence　of　high　concentrations　of　cement　raw　materials　may　influence　SNCR　denitration　reaction　process　in　cement　kilns.　Therefore,　studying　the　effect　of　CaO　which　occupy　the　major　composition　of　cement　raw　material　is　very　important　in　SNCR　process.　In　this　study　the　influence　of　CaO　on　the　SNCR　deNOx　process　was　investigated　by　simulating　SNCR　reaction　at　temperature　that　ranges　from　750°C　to　1100°C　with　different　normalized　stoichiometric　ratio.　The　experimental　results　demonstrate　that　the　addition　of　CaO　increases　the　optimum　denitration　temperature　to　1100°C,　but　it　has　no　effect　on　normalized　stoichiometric　ratio.　In　the　whole　reaction　process　NH3　not　only　restores　NO　to　O2　but　also　reacts　with　O2　to　NO.　Since　the　adsorption　of　NH3　on　CaO　surface,　in　the　temperature　range　of　750°C　-850°C　the　addition　of　CaO　promotes　the　reaction　of　NH3　and　O2　and　increases　NOX　concentration.　However,　in　the　temperature　range　of　850°C　-1000°C　it　not　only　promotes　NH3　oxidation　but　also　inhibits　the　reduction　reaction　of　NH3,　thereby　the　denitration　reaction　is　inhibited.　In　the　temperature　range　of　1050°C　-1100°C　the　denitration　reaction　is　promoted　due　to　the　NH3　desorption　from　CaO　surface.　©　2016　Trans　Tech　Publications,　Switzerland.