The impacts of electric field applied in MBR (EMBR) for treating phenol wastewater and membrane antifouling mechanism were systematically investigated. Phenol degradation rate increased from 0 to 0.8 V/cm, while decreased from 0.8 to 1.75 V/cm, which significantly positively correlated with key enzymes. The membrane fouling rate of EMBR gradually slowed down with voltage increasing. The applied voltage significantly reduced EPS contents, and altered its compositions probably due to H2O2 oxidation, which were the major reasons for membrane antifouling. Red shift in UV-Vis spectrum at 210-220 nm and reduction of fluorescence emission intensity from tryptophan protein-like substances in EPS reduced the energy requirement for electrons transition of electron-donating groups with voltage increasing. Positively charged bond -NH2 decreased and negatively charged bond COO- increased in EPS with voltage increasing, which led to the increase of absolute value of zeta potential and then remarkable augmented of electrostatic repulsion between sludge and membrane.