Actual　domestic　sewage　was　treated　by　SBR　process.　Limited　filamentous　bulking　was　induced　by　low　dissolved　oxygen　at　low　temperature,　and　the　SVI　were　maintained　150-200　mL/g.　The　occurrence　of　limited　filamentous　bulking　at　low　temperature　and　the　growth　of　microorganism　were　researched;　the　technique　of　FISH　was　adopted　to　identify　the　species　of　the　dominant　filamentous　bacteria　in　the　state　of　limited　filamentous　bulking,　and　the　result　showed　that　the　filamentous　bacteria　that　led　to　limited　filamentous　bulking　was　microthrix　parvicella　(MPA223).　Compared　to　the　status　at　normal　dissolved　oxygen,　the　removal　rate　of　COD　and　PO43--P　increased　to　80%　and　90%,　while　the　removal　rate　of　NH4+-N　and　TN　decreased　to　52%　and　28%　respectively　during　limited　filamentous　bulking.　And　the　data　also　showed　that　low　dissolved　oxygen　led　to　the　phenomenon　of　simultaneous　nitration-denitration　(SND),　about　15%　of　the　nitrogen　was　removed　by　SND.