At　normal　temperature　of　(19±1)°C,　without　the　addition　of　external　carbon　sources,　simultaneous　nitrification　denitrification　via　nitrite　(SND　via　nitrite)　was　studied　in　a　lab-scale　SBR　treating　domestic　wastewater　with　low　ratio　of　carbon　to　nitrogen.　The　results　showed　that　under　the　long　sludge　retention　time　(SRT)　of　50~66d　and　limited　aeration　with　the　maximum　ρDO　below　2.0mg/L　and　the　average　ρDO　of　0.65mg/L,　partial　nitrification　to　nitrite　was　successfully　achieved　with　ρ(NO2--N)/　ρ(NOx--N)　over　95%.　Moreover,　denitrification　occurred　during　the　above　aerobic　nitrification　phase.　The　average　ρTN　removal　efficiency　by　SND　via　nitrite　maintained　52%,　and　the　maximum　was　up　to　63.1%.　The　low　ρDO　concentration　under　limited　aeration　is　the　key　factor　to　achieving　SND　via　nitrite.　Under　a　long　time　operation　with　low　ρDO　concentrations,　the　altering　of　nitrifying　communities,　micro-environment　for　denitrifiers　growth　and　biodegradation　characteristics　of　ρCOD　and　ρ(NH4+-N)　promoted　the　occurrence　of　SND　via　nitrite.