Abstract: A moving bed biofilm reactor(MBBR)-membrane bioreactor(MBR) combined process was constructed to treat domestic wastewater, and the removal effect of pollutant and membrane fouling were investigated. The results showed that the removal rate of NH_4^+-N and COD could reach 97% by MBBR-MBR. The membrane suction pressure in MBR was characterized by a slow increase and then a rapid increase with the extension of the running time. Extracellular polymeric substances (EPS) and soluble microbial products (SMP) were important factors influencing membrane fouling. Ordinary chemical cleaning did not restore the MBR membrane module to the level of the new, showing irreversibility. The apparent molecular weight distribution of EPS was more extensive, while the apparent molecular weight of SMP exhibited a single peak characteristic. SMP was mainly composed of small molecular weight substances.