The influence of activated sludge properties on membrane fouling was investigated using statistical method. The results show that extracelluler polymeric substances (EPS), soluble microbial products (SMP), suspended solids in the supernatant (SSs), dynamic viscosity (micro), relative hydrophobicity (RH) and Zeta potential all have a significant influence on membrane permeability during microfiltration of activated sludge wastewater. The pearson's correlation coefficient (r(p)) for linear correlations between membrane fouling resistance and these sludge properties are 0.898, 0.712, 0.810, 0.691, 0.837, -0.881, respectively. The statistical results also show that SMP, micro, SSs, Zeta potential, and RH are mostly determined by EPS, indicating that EPS is the main and essential factor affecting membrane fouling in activated sludge properties. The pearson's correlation coefficient (r(p)) for linear correlations between total EPS and other sludge properties are 0.682, 0.633, 0.783, -0.953, 0.877, respectively. EPS should be controlled in the operation of membrane bioreactor to achieve a suitable permeation.