Using　a　lab-scale　batch　sequencing　reactor(SBR),　advanced　nitrogen　removal　from　municipal　wastewater　and　stabilizing　short-cut　nitrification　and　denitrification,　as　well　as　N2O　emission,　were　investigated　by　on-line　pH　controlling.　The　aeration　rate　was　controlled　at　60　L/h.　It　revealed　that　by　step-feeing　pattern,　less　N2O　was　emitted　and　less　external　carbon　for　denitrification　was　required.　The　increasing　feeding　mode　was　efficient　for　reducing　the　NO2-　accumulation　and　N2O　emission　when　organic　carbon　in　the　influent　was　insufficient.　The　N2O-N　emission　were　11.1,　8.86　and　5.04　mg/L　for　one-time　feeding,　two　equal　feeding　and　two　increasing　feeding　mode　respectively.　The　accumulation　of　NO2--N　during　nitrogen　removal　process　contributed　to　the　production　of　N2O.　The　denitrification　process　of　AOB　under　low　DO　level　might　be　the　cause　of　N2O　production　in　which　NO2-　was　used　as　electron　acceptor　and　NH4+　as　electron　donor.