In　order　to　investigate　the　metabolism　of　Candidatus　Accumulibacter　Phosphates　(a　well-known　phosphate　accumulating　organism)　and　its　affecting　factors,　anaerobic-aerobic　SBR　reactor　was　performed　to　incubate　polyphosphate　accumulating　organism　(PAO)　using　synthetical　sewage,　and　the　content　of　PAOs　reached　more　than　80%.　Based　on　the　enriched　culture,　several　batch　experiments　were　taken.　The　results　indicated　that　when　acetate　and　nitrite　were　both　in　the　reactor(in　60min),　with　the　increasing　of　the　initial　nitrite,　Accumulibacter　released　much　more　PO43--P,　whereas　the　acetate　uptake　rate　and　the　amount　of　accumulated　PHA　decreased.　After　60min,　the　concentration　of　phosphate,　nitrate　and　PHA　were　all　degressive,　suggesting　that　denitrifying　phosphorus　removal　were　occurred.　The　results　suggested　that　there　were　denitrifying　phosphorus　organisms.　Besides,　there　were　a　part　of　PAOs　which　could　be　poisoned　by　nitrite　in　this　system.