To　achieve　the　reduction　of　emissions　and　control　of　non-CO2　greenhouse　gases　in　municipal　wastewater　treatment　plants,　this　study　conducted　a　one-year　monitoring　of　N2O　in　the　A2O　process　of　a　large　municipal　wastewater　treatment　plant　in　Beijing.　N2O　released　from　the　water　surface　of　the　A2O　process　was　collected　by　using　a　gas　flux　chamber,　and　the　key　influencing　factors　affecting　N2O　were　analysed　using　statistics.　The　results　showed　that　N2O　was　not　easy　to　be　released　under　non-aerated　conditions,　and　the　aerobic　zone　was　its　main　emission　area.　Temperature　leads　to　high　N2O　emissions　in　winter　and　low　in　summer.　Correlation　analyses　showed　that　NO2-N　is　one　of　the　most　critical　factors　affecting　N2O　production,　and　its　accumulation　level　directly　affects　the　amount　of　N2O　produced　in　the　system.　DO　also　has　a　great　influence　on　the　production　of　N2O,　and　the　amount　of　N2O　produced　decreases　with　the　increase　of　the　DO　concentration,　and　the　effect　on　the　enzyme　activity　also　makes　the　pH　have　a　significant　effect　on　the　production　of　N2O.