The　effects　of　different　pH　(5,　7,　9,　unregulated)　on　performance　of　waste　activated　sludge　(WAS)　coupling　with　denitrification　were　investigated　to　study　sludge　dissolution,　substances　release,　sludge　reduction　and　denitrification　performance.　In　the　batch　experiment　controlling　temperature　at　(30±1)°C,　NO2--N　was　added　into　the　system.　The　results　indicate　that　when　pH=5,　the　concentrations　of　carbohydrate　is　much　higher　than　that　at　other　pH　values　and　the　highest　occurs　at　the　18th　day,　and　it　is　648.9　mg/L;　when　pH=5　and　9,　the　concentration　of　protein　is　higher,　and　the　highest　occurred　when　pH=9　at　the　15th　day,　and　it　is　701.5　mg/L;　when　pH=5,　PO43--P　concentration　is　always　higher　than　that　at　pH　9,　however,　NH4+-N　concentration　is　higher　at　pH=9.　The　system　at　different　pH　all　performed　sludge　reduction.　In　addition,　the　order　of　denitrification　performance　(from　good　to　bad)　is　pH=9,　pH=7,　pH　unregulated　and　pH=5　according　to　NO2--N　accumulation.　In　general,　the　optimal　pH　of　waste　activated　sludge　fermentation　coupling　with　denitrification　is　9.