Aiming　at　the　increasing　concentration　of　N2O　in　the　atmosphere　year　by　year,　nitrification　and　denitrification　in　biological　nitrogen　removal　process　are　considered　as　the　major　sources　for　N2O　production　in　wastewater　treatment.　The　emission　mechanics,　affecting　factors　such　as　temperature,　pH,　dissolved　oxygen　concentration　(DO),　SRT　and　carbon　to　nitrogen　ratio　(C/N)　of　wastewater　are　discussed　in　this　paper.　Finally,　the　preliminary　strategies　for　N2O　emission　control　from　wastewater　treatment　of　biological　nitrogen　removal　are　put　forward　based　on　microorganism　population　optimization　and　process　operation　which　affect　the　N2O　production:　the　maintenance　of　relative　long　SRT,　high　DO　concentration　during　aeration,　strict　anoxic　condition　in　denitrifying　and　neutral　or　alkaline　condition.