Abstract: A pilot study was carried out to treat inferior Ⅴ grade micro-polluted river water by Anoxic/Membrane bioreactor (A/MBR) combined with pretreatment with coagulation and sedimentation. The process conditions and measures were investigated to achieve good effluent quality in terms of treating the micro-polluted river water with high concentrations of nitrogen and phosphorus and low concentrations of carbon. The pilot system with a capacity of 10 m³/d worked at air flow-rate 8 m³/h and HRT of the sedimentation tank, anoxic tank and membrane tank at 25 min, 0.8 h and 2.5 h respectively, and under the additional conditions of MLSS concentration 6.0～6.5 g/L. The polymeric aluminums (PAC) were dosed 10 mg/L in the sedimentation tank and 5 mg/L in the membrane tank respectively, and about two times the theoretical methanol quantity was dosed in the anoxic tank. The results showed that the mass concentrations of COD_Cr, BOD₅, NH₃-N and TP in the effluent could meet the grade Ⅲ standards of Environmental Quality Standards for Surface Water (GB3838-2002), and TN was less than 15 mg/L.