Abstract: The treatment of the mixed wastewater from college dormitory and canteen by a submerged flat membrane bioreactor (MBR) system was studied experimentally. The anaerobic/oxic (A/O) MBR system has a capacity to treat wastewater up to 4 m³/d, through which the B0D5 and CODCr in the influent are 90-450 mg · L^-1 and 120-900 mg · L^-1, and they in the effluent are 5-25 mg · L and 8-45 mg · L^-1 respectively, i.e. the removal rates are both over 90%. In addition, how to get rid of color contamination of effluent and membrane fouling was investigated. It was found that activated carbon can remove the contaminated color effectively, and the membrane can work well after cleaned up mechanically and chemically. A conclusion was drawn that the submerged flat MBR system is applicable to medium/small-scale domestic even industrial organic wastewater treatment with broad prospects in application.