The　large　amount　of　intermediate　nitrous　oxide　(N2O)　production　from　denitrifying　phosphorus　removal　(DPR)　increases　the　carbon　footprint　of　wastewater　treatment.　However,　there　is　a　lack　of　detailed　understanding　of　the　interrelationships　between　denitrifying　polyphosphate-accumulating　organisms　(DPAOs)　and　denitrifying　glycogen-accumulating　organisms　(DGAOs)　on　N2O　production　during　DPR.　In　this　work,　a　mathematical　model　was　developed　for　the　first　time　to　describe　dynamic　N2O　production　in　the　DPR　system　coexisting　DPAOs　and　DGAOs.　The　model　took　into　account　a　four-step　subsequent　denitrification　of　nitrate,　nitrite,　nitric　oxide,　and　N2O.　The　validity　of　model　was　fully　tested　by　comparing　simulation　studies　with　experimental　data　from　three　independent　reports　on　DPR,　which　satisfactorily　described　the　dynamics　of　N2O　production,　nitrogen　oxide　reduction,　phosphate　release　and　uptake,　and　intracellular　polymers　turnover.　The　validated　model　could　clarify　the　source　and　pathways　of　N2O　production.　Subsequently,　the　combined　effects　of　key　operational　conditions　on　the　overall　N2O　production,　DPAOs　and　DGAOs　competition,　and　nutrients　removal　efficiency　were　investigated　by　model　simulation.　Simulation　results　showed　higher　polyhydroxyalkanoate　storage　rate　of　DGAOs　than　that　of　DPAOs　during　anaerobic　stage　and　the　preference　of　DGAOs　for　nitrate　electron　acceptor　during　anoxic　stage.　DGAOs　dominated　the　growth　competition　over　DPAOs　at　low　COD　(<150　mg/L)　and　high　nitrate　(>35　mg/l)　conditions,　leading　to　the　anoxic　storage　of　glycogen　by　DGAOs　as　the　main　pathway　of　N2O　production.　In　addition,　both　N2O　production　and　generation　pathways　in　the　system　possessed　greater　variability　compared　to　single　DGAOs　or　DPAOs　system,　further　indicating　the　necessity　of　this　model.　©　2022　Elsevier　B.V.