Abstract: Because of the trait of denitrifying and phosphate-accumulating simultaneously,the requirement of carbon resources for denitrifying phosphate-accumulating organism(DPAO)will be minimized,which may provide a new routine to resolve the problem of lacking carbon resource.The discovery attracts many researchers’ attention.In this paper,a simple method of isolation for DPAO has been established.One pure denitrifying phosphate-accumulating organism(RC11)from pond sediment has been adopted,and the influences of external carbon resource and nitrate on the pure strain RC11 were studied.The results indicated that the strain RC11 could acquire energy from oxidizing external carbon resource using oxygen as electron accetpor directly to produce polyphosphate,but in anaerobic stage,the strain RC11 could not use nitrite as the electron acceptor to carry out denitrifying phosphorus uptake.With no external carbon resource,the strain RC11 could acquire energy from oxidizing PHB using nitrate as electron acceptor to produce polyphosphate,but phosphate will be released from cell in high concentration of nitrite because nitrite nitrogen could not be the electron acceptor to replace molecule oxygen; the strain RC11 could use nitrate as electron acceptor to produce polyphosphate in anaerobic stage.