To　investigate　the　responding　behavior　of　denitrifying　bacteria　to　different　carbon　source　(i.e.,　methanol,　ethanol,　sodium　acetate,　sodiumpropionate,　glucose,　domestic　wastewater　and　endogenous　carbon　source),　several　batch　experiments　using　the　sludge　from　the　Carrousel　oxidation　ditch　were　carried　out　at　15.4　degrees　C　+/-　0.8　degrees　C.　The　results　from　sodium　acetate　feeding　experiment　show　the　highest　maximum　specific　denitrification　rate　(MSDR),　which　is　6.51　mg/(g　x　h).　However,　the　denitrificaion　yield,　which　is　0.48,　is　at　lowest　level　and　an　obvious　accumulating　of　nitrite　is　observed.　Compared　to　the　other　sole　carbon　source,　a　lower　MSDR,　0.91　mg/(g　x　h)　is　shown　when　methanol　is　used　as　carbon　source,　which　also　suggests　that　the　sufficient　adaptation　time　should　be　promised　for　denitrifying　bacteria.　When　the　reactor　is　operated　without　exogenous　carbon　source,　denitrifying　bacteria　can　use　the　endogenous　carbon　source　as　electron　donor　for　denitrification,　but　the　specific　denitrification　rate　is　at　lowest　level　accordingly.　The　MSDR　value　of　3.63　mg/(g　x　h)　is　obtained　with　fermented　domestic　wastewater　feeding,　which　is　equivalent　to　the　MSDR　attained　from　the　test　using　VFAs　as　carbon　source.　Though　the　MSDR　decreases　a　lot　at　low　temperature,　external　carbon　source　addition　improves　the　denitrification　performance　to　some　extent　definitely.