It　is　not　successful　to　denitrify　waste-water　with　high　content　of　salt　by　freshwater　activated　sludge　because　of　salinity　choking.　To　overcome　this　problem,　halophilic　activated　sludge　must　be　developed.　In　this　study,　activated　sediment　at　estuary　of　a　river　was　collected　and　cultured　to　get　halophilic　activated　sludge.　The　effect　of　key　factors,　such　as　salinity,　temperature,　pH　and　carbon　source　etc.,　on　denitrifying-nitrite　performance　of　the　halophilic　activated　sludge　was　studied.　The　results　show　that　nitrite　can　be　denitrified　by　the　halophilic　system　via　utilizing　it　as　electron　acceptor.　As　a　result,　the　halophilic　activated　sludge　is　of　ability　to　denitrify　highly　saline　wastewater.　At　38　g·L-1　salinity　environment,　the　maximum　specific　denitrification　rate　of　the　biological　system　is　3.29　mg　N·(g　VSS)-1·h-1.　These　key　operation　parameters　were　optimized　for　further　engineering　design:　the　optimal　survival　salinity　is　15-51　g·L-1　and　pH　8.0-9.0.　Carbon　source　has　a　great　influence　on　denitrification　rate.　Among　methanol,　acetate,　propionic　and　glucose　tested,　methanol　is　the　best　because　it　is　beneficial　electron　donors.　As　a　new　different　biological　system,　the　halophilic　activated　sludge,　it　is　of　important　significance　for　treatment　of　saline　wastewater　to　establish　their　characteristic　of　denitrification　and　influencing　factors.　©　2012　All　Rights　Reserved.