The　production　of　N2O　of　domestic　sewage　with　different　step-feeding　modes　was　inspected　during　shortcut　biological　nitrogen　removal.　Sequencing　batch　reactor　was　used　in　the　experiment　and　the　aeration　was　controlled　at　60　L/h.　The　results　show　that　N2O　is　mainly　produced　in　the　nitrification　stage;　the　accumulation　of　NO2-　decreases　along　with　the　increase　of　steps.　The　N2O　output　increasing　order　with　different　feeding　modes　is　as　follows　one-step　influent,　two-step　influent,　and　three-step　influent.　The　reason　is　that　ammonia-oxidizing　bacteria　used　nitrite　as　electron　acceptors　and　reducing　hydrogen　or　ammonia　as　electron　donors　for　aerobic　denitrification.