Recently, the dispersion and distribution of inorganic materials has become a high issue in membrane synthesis and performance. In this work, 3-aminopropyltriethoxysilane modified SiO2 (APTES-SiO2) filled polyethersulfone (PES) membranes were prepared via one-pot Stober method and dry-wet phase inversion. APTES-SiO2 particles with different concentration were incorporated in PES matrix to fabricate the composite membranes. Prepared membranes were characterized using porosity, SEM, hydrophilicity, FTIR, tensile strength and pore size. Separation efficiencies of membranes were studied in respect to fouling, oil rejection, permeate flux and pure water flux (PWF). As compared with previous organic-inorganic membranes prepared by the conventional method, the new PES/APTES modified SiO2 membrane presents a more uniform dispersion of particles on the membrane surface even at high loading. The best composite membrane was attained when the content of APTES-SiO2 was 2.5 wt%. In this case, the PWF increased from 219.397 to 227.500 kg/m(2) h, the permeate flux increased from 134.63 to 159.88 kg/m(2) h and oil removal efficiency increased from 97.23 to 99.87%. This work demonstrates that by modifying the silica with APTES can be an effective approach to enhance particle dispersion, physical properties and can simultaneously boost the performance of PES/APTES-SiO2 HF membranes for wastewater applications.