To　achieve　energy-efficient　denitrifying　phosphorus　removal　via　nitrite　pathway　from　sewage,　interaction　of　＂Candidatus　Accumulibacter＂　and　nitrifying　bacteria　was　investigated　in　a　continuous-flow　process.　When　nitrite　in　returned　sludge　of　secondary　settler　was　above　13　mg/L,　nitrite　inhibition　on　anaerobic　P-release　of　polyphosphate　organisms　(PAOs)　occurred.　Clades　IIC　and　IID　were　dominant,　reaching　3.1%-11.9%　of　total　bacteria.　Clade　IIC　was　sensitive　to　nitrite.　Under　low　concentration　of　nitrite　(＜　8　mg/L),　Glade　IIC　primarily　contributed　to　anoxic　P-uptake.　Clade　IID　had　a　strong　tolerance　to　nitrite　exposure.　At　high　nitrite　level　(above　16　mg/L),　anoxic　P-uptake　was　mainly　performed　by　Glade　IID　due　to　its　strong　tolerance　to　nitrite　exposure.　Ammonia　oxidizing　bacteria　(AOB),　nitrite　oxidizing　bacteria　(NOB)　and　Accumulibacter　interacted　through　variations　of　nitrite　accumulation.　High　AOB　abundance　coupled　with　inhibition　of　NOB　favored　denitrifying　phosphorus　removal　by　Glade　IID.　All　Accumulibacter　lineages　were　sorted　into　four　clades　of　Type　II.　The　most　dominant　ppk1　gene　homologs　were　affiliated　with　Glade　IID,　accounting　for　69%　of　ppk1　clone　library,　and　thus　played　an　important　role　in　denitrifying　phosphorus　removal　via　nitrite　pathway.