Thin film composite nanofiltration membranes were fabricated by interfacial polymerization of polyethyleneimine and triphthaloyldechloride on the top surface of the polysulfone substrate. Different contents of SiO2 nanoparticles were added to the aqueous solution for modification of PEI-based NF membrane. Fourier transform infrared spectra of membranes showed the new functional groups on the surface of membrane due to the presence of SiO2 nanopartides. The contact angle measurement confirmed the improvement on the hydrophilic properties of the surface. Scanning Electron Microscope images showed that the SiO2 nanopartides well dispersed on the surface structure of the modified membranes. The roughness parameters indicated that the surface of the fabricated membranes became rougher after adding SiO2 nanopartides. By adding SiO2 nanoparticles, the membrane performance showed growing trend in the case of flux, but for rejection a slight decrease was observed at first, then it was changed to growing trend by the further increasing amount of SiO2 nanoparticles. (C) 2015 Elsevier B.V. All rights reserved.