To enhance the membrane bioreactor treatment effect, improve the sludge characteristics, parallel compared experiments of the submerged membrane bioreactor of adding coagulant (PAFC) and the normal membrane dealing with domestic wastewater was carried out. The results showed that coagulation membrane bioreactor was significantly higher treatment effect than normal membrane bioreactor, the removal efficiency of coagulation-MBR on COD, NH 3 -N was 92.04%, 96.55%, the normal membrane bioreactor was 90.26%, 91.74%. As can be seen from the operating pressure, sludge microscope photographs, after adding PAFC, membrane fouling was prevented effectively.