Under　room　temperature　(20~25°C),　in　intermittent　aeration　sequencing　batch　reactors　1　#,　2　#,　3　#,　it　was　studied　that　effects　of　different　ratios　of　aeration　time　and　anaerobic　time　(3:1,　3:2,　3:3)　on　the　nitrite　accumulation,　the　stability　of　nitrosation,　the　pollutants　removal　efficiency　and　sludge　settling　performance　with　domestic　wastewater.　The　smaller　the　ratio　of　aeration　time　and　anaerobic　time　within　a　certain　rangeis,　the　more　beneficial　to　the　accumulation　of　nitriteis.　It　realized　the　start-up　of　nitrosation　by　35d,　30d,　29d　respectively.　In　stable　operation　stage,　the　removal　of　ammonia　nitrogen　volume　of　load　were　0.57,　0.48,　0.40　kgN/m3　drespectively.　The　smaller　the　ratio　of　aeration　time　and　anaerobic　timeis,　the　smaller　ammonia　nitrogen　removal　load　was.　The　differences　of　COD　removal　effect　were　not　obvious.　At　82d　the　nitrosation　rate　of　1　#　showed　a　trend　of　gradual　decline,　but　it　had　a　stable　operation　in　2　#,　3　#.　So　the　smaller　the　ratio　of　aeration　time　and　anaerobic　timeis,　the　more　conducive　to　maintain　the　stability　of　nitrosation,　and　the　better　sludge　settling　performance　was.