Sewage　nitritation　is　a　promising　process　for　nitrogen　removal,　but　its　practical　application　is　limited　by　long　start-up　period　and　unstable　operation.　In　this　study,　hydroxylamine　(NH2OH)　addition　and　real-time　aeration　control　strategies　were　adopted　for　the　promotion　of　sewage　nitritation　in　a　sequencing　batch　reactor.　Initially,　4.5　mg/L　NH2OH　was　added　into　reactor　every　24　h　to　establish　nitritation,　increasing　the　nitrite　accumulation　ratio　(NAR)　from　1.7%　to　93%　in　19　d.　In　the　following　period,　NH2OH　addition　was　stopped　and　nitritation　remained　stable　over　55　d,　with　NAR　of　97%　by　real-time　aeration　control.　The　aeration　duration　was　determined　by　characteristic　points　on　pH　curve.　The　main　genera　of　nitrite　oxidizing　bacteria,　Nitrobacter　and　Nitrospira,　were　both　eliminated　from　the　system,　supporting　the　long-term　stability　of　nitritation.　Overall,　NH2OH　addition　and　real-time　aeration　control　is　an　excellent　strategy　for　establishing　and　maintaining　effective　sewage　nitritation.