Membrane bioreactor technology was used to treat the different salinity of domestic sewage under the conditions of COD_Mn of 47.4～112.4 mg·L^-1,NH3-N of 27.5～49.7 mg·L^-1,TN of 35.2～57.1 mg·L^-1,pH of 6.0～8.0,DO of 2.8～6.2 mg·L^-1,MLSS of 5880～6823 mg·L^-1,temperature of 20～27 ℃.The results show that average removal rate of COD_Mn is 88.1%,85.1%,84.0%,respectively,average removal rate of NH₃-N is 91.9%,90.6%,89.7%,and average removal rate of TN is 47.1%,41.1%,35.7% respectively,when the salinity of the sewage is 0.5%,1.0% and 1.5%,respectively. Under the same salinity,the items monitored first decrease and then show a stable trend after the rise.On the whole,the removal rate of COD,NH₃-N,TN and MLSS all decline with salinity increasing.The extracellular polymeric substance(EPS) excreted by microorganisms under the high salinity conditions is mainly responsible for membrane fouling.