An　anaerobic-oxic　(A/O)　biological　phosphorus　removal　reactor　was　operated　to　study　the　effect　of　nitrite　on　phosphate　uptake.　The　phosphorus　uptake　profile　was　determined　under　different　operating　conditions.　The　results　indicated　that　in　addition　to　oxygen　and　nitrate　(DPBNa,　nitrate　denitrifying　phosphorus　removal),　to　some　extent,　nitrite　could　also　serve　as　an　electron　acceptor　to　achieve　nitrite　denitrifying　phosphorus　removal　(DPB　Ni).　The　quantity　and　rate　of　phosphorus　uptake　of　DPBNi,　however,　were　evidently　lower　than　that　of　DPBNa.　The　experiment　results　revealed　that　nitrite　would　bring　toxic　action　to　phosphate-accumulating　organisms　(PAOs)　when　NO2　--N　≥　93.7　mg/L.　The　nitrite　existing　in　the　anoxic　reactor　made　no　difference　to　the　quantity　and　rate　of　denitrifying　phosphorus　removal,　but　it　could　reduce　the　consumption　of　nitrate.　Moreover,　the　data　showed　that　the　aerobic　phosphate　uptake　of　DPBNi　was　lower　than　that　of　anaerobic　phosphorus-released　sludge　in　a　traditional　A/O　process.　However,　there　was　not　much　difference　between　these　two　kinds　of　sludge　in　terms　of　the　total　phosphorus　uptake　quantity　and　the　effluent　quality.　©　Higher　Education　Press　2007.