Phosphate　accumulating　organisms　(PAOs)　has　been　enriched　successfully　in　an　anaerobic-aerobic　sequencing　batch　reactor　(AO-SBR)　with　the　influent　of　the　domestic　sewage　with　C/P　ratio　greater　than　50.The　average　anaerobic　phosphorus　release　amount　was　15　mg•L-1.　The　concentration　of　effluent　PO_4^(3-)-P　was　less　than　0.5　mg•L-1.　On　the　74　th　day,　the　operation　mode　was　adjusted　to　anaerobic-anoxic-aerobic,　and　NO_3^--N　was　added　at　the　beginning　of　anoxic　zone　to　enrich　the　denitrifying　phosphorus　accumulating　bacteria(DPB).　The　best　efficiency　of　denitrifying　phosphorus　removal　performance　were　acquired　when　the　influent　COD　concentration　was　250　mg•L-1　and　the　NO_3^--N　concentration　was　constant　in　the　system.　Meanwhile　the　ratio　of　average　denitrifying　phosphorus　removal　to　phosphorus　removal　was　87.1%.　Anoxic　pH　effect　tests　showed　that　the　rate　of　denitrifying　phosphorus　removal　is　related　to　the　pH　value,　DPB　preferred　higher　pH　for　phosphorus　removal,　and　the　maximum　specific　phosphorus　removal　rate　of　2.1　mg　P•(g　VSS•h)-1　is　obtained　at　pH=7.0.　In　the　subsequent　experiments,　NO_3^--N　was　supplied　from　the　effluent　reactor　and　drainage　ratio　was　increased.　These　methods　ensured　that　the　pH　of　the　anaerobic　reactor　was　closed　to　7.0.　The　comparison　with　the　unadjusted　stage　showed　that　the　rate　of　denitrifying　phosphorus　removal　increased.　The　reactor　was　operated　for　160　days,　and　the　COD　removal　and　denitrifying　phosphorus　removal　process　were　stably　completed.　©　All　Right　Reserved.