The gradual increase of salt concentration (0 to 35g-NaCl/L) on the performance of membrane bioreactor (MBR) was studied. The uptake rate of dissolved organic carbon and ammonia decreased from around 17.0mg-DOC/g-MLVSS.d to 1.8mg-DOC/g-MLVSS.d and from 8.2mg-NH 4 -N/g-MLVSS.d to 0mg-NH 4 -N/g-MLVSS.d respectively when salt concentration reached to 35g-NaCl/L. Similarly the specific oxygen uptake rate (SOUR) reduced from 8 to 9 to around 0.3mg-O 2 /g-MLVSS.h. The removal of bio-polymers, humic acids, building blocks and low molecular weight neutral decreased with increase in salt concentration. The concentration of dissolved organic nitrogen (DON) in bio-polymer increased from 0.05 to 3.31mg/L when the salt concentration reached to 35g-NaCl/L. This study provides good information for understanding the effect of continuous increase of salt concentration in treating saline wastewater in a MBR process.