The treatment efficiency by the gas-water alternate membrane bioreactor(AMBR) on domestic sewage was investigated through a pilot-scale study in order to get better application effect in the practical engineering.The results showed that: AMBR had good COD and NH4+-N removal effect when the C/N ratio of raw domestic sewage was 4,and the COD and NH4+-N concentration in effluent under 20 mg/L and 5 mg/L.But it’s not good at TN removal because of its low C/N ratio,and the TN concentration in effluent was 22.4 mg/L.When the C/N ratio of raw water increased to 6 according to adding glucose in raw domestic sewage,the TN removal efficiency by AMBR was increased to 66%,and the effluent TN was only 13 mg/L,which met the First A-level requirement of China.Meanwhile,the COD and NH4+-N removal effect by AMBR was unaffected by the change of the raw water’s C/N ration.The trans-membrane pressure was maintained about-20 kPa indicated that AMBR also had good membrane fouling alleviating effect.