The combined process of the powdered active carbon(PAC) and the ultrafiltration(UF) was used to treat effluent of sedimentation tank in a waterworks.The influences of the PAC dosage(0、10、20 and 40 mg.L-1) on the UF were studied.The results showed that adding PAC to the system could enhance the removal efficiencies of the PAC-UF for CODMn,UV254.The larger amount PAC added,the higher removal efficiency achieved.The addition of PAC could mitigate membrane fouling,and played an important role in the long-time stable operation of the PAC.And the performance of membrane could be recovered after chemical backwashing.