A　bench-scale　cyclic　activated　sludge　technology　(CAST)　was　operated　to　study　the　biological　phosphorus　removal　performance　and　a　series　of　batch　tests　was　carried　out　to　demonstrate　the　accumulation　of　denitrifying　polyphosphate-accumulating　organisms　(DNPAOs)　in　CAST　system.　Under　all　operating　conditions,　step-feed　CAST　with　enough　carbon　sources　in　influent　had　the　highest　nitrogen　and　phosphorus　removal　efficiency　as　well　as　good　sludge　settling　performance.　The　average　removal　rate　of　COD,　NH4+-N,　PO43--P　and　total　nitrogen　(TN)　was　88.2%,　98.7%,　97.5%　and　92.1%,　respectively.　The　average　sludge　volume　index　(SVI)　was　133　mL/g.　The　optimum　anaerobic/aerobic/anoxic　(AOA)　conditions　for　the　cultivation　of　DNPAOs　could　be　achieved　by　alternating　anoxic/oxic　operational　strategy,　thus　a　significant　denitrifying　phosphorus　removal　occurred　in　step-feed　CAST.　The　denitrification　of　NOx(-)-N　completed　quickly　due　to　step-feed　operation　and　enough　carbon　sources,　which　could　enhance　phosphorus　release　and　further　phosphorus　uptake　capability　of　the　system.　Batch　tests　also　proved　that　polyphosphate-accumulating　organisms　(PAOs)　in　the　step-feed　process　had　strong　denitrifying　phosphorus　removal　capacity.　Both　nitrate　and　nitrite　could　be　used　as　electron　acceptors　in　denitrifying　phosphorus　removal.　Low　COD　supply　with　step-feed　operation　strategy　would　favor　DNPAOs　accumulation.