Abstract: In order to ensure that the MBR not only obtains high quality effluent but also lessen the membrane fouling to prolong the working period of the membrane module,the powdered activated carbon(PAC)was added into the bioreactor(the concentration of PAC was 1500mg/L).And the MBR has run continuously for 120 days with constant temperature(30℃),constant membrane flux(7L/(m²·h))and intermittent pump (the outlet pump run for 10 minutes and rests for 3 minutes).The experimental results showe that the biofilm on the PAC as carrier is formed,thus the biofilm and the activated sludge in membrane bioreactor produce new ecosystem which can improve the wastewater removal efficiency.In addition PAC changes the properties of the mixed liquor and the structure of cake layer on the surface of membrane module,and the filtration resistance is reduced.It is an effective way to lessen membrane fouling.