The　characteristics　of　denitrifying　phosphorus　removal　in　a　lab-scale　two-sludge　anaerobic-anoxic/nitrification　SBR　(A2NSBR)　system　were　studied　fed　with　domestic　wastewater.　The　influence　of　some　key　operation　parameters,　like　C/P,　C/N,　and　HRT,　were　examined　using　parallel　tests.　pH,　dissolved　oxygen　(DO)　and　redox　potential　(ORP)　were　monitored　on　line　to　validate　whether　they　could　be　used　as　the　control　parameters　for　this　denitrifying　phosphorus　removal　process.　Results　indicated　that　P　removal　efficiency　showed　an　increased　trend　on　the　whole　with　the　increase　of　the　C/P.　When　the　influent　C/P　was　greater　than　19.39,　good　phosphorus　removal　efficiency　was　achieved.　However,　the　phosphorus　removal　efficiency　deteriorated　once　the　influent　C/P　decreased　less　than　15.36.　On　the　other　hand,　relatively　good　phosphorus　removal　efficiency　could　be　maintained　in　the　A2NSBR　system　even　at　a　low　C/N　ratio,　though　the　denitrification　efficiency　decrease　instead.　It　is　also　found　that　increasing　the　influent　C/N　increased　the　PHB　amount　stored　by　polyphosphate　accumulating　organisms　(PAO)　and　therefore　the　ultimate　denitrification　and　phosphorus　removal　efficiency　were　both　improved.　For　an　excessively　high　C/N,　the　incompletely　reacted　COD　will　be　residual　to　anoxic　stage.　Thus,　the　pure　denitrification　reaction,　which　preferentially　supports　OHOs,　becomes　the　dominant　reaction.　This　decreases　the　amount　of　available　electron　acceptors　for　denitrifying　polyphosphate　accumulating　organisms　(DNPAOs)　at　the　anoxic　stage　which　eventually　impacts　the　anoxic　phosphorus　removal　capacity.　In　addition,　since　A2NSBR　has　two　completely　independent　SBR　systems,　it　benefits　to　establish　a　process　control　system　in　terms　of　the　parameters　DO,　ORP,　and　pH.