Surface functionalization of graphene oxide (GO) nanoplates was performed by glycidyl polyhedral oligosilsesquioxane (POSS), and was used to fabrication of polyetherimide (PEI) based nanofiltration membranes by phase inversion method. The prepared membranes characterized by Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), X-ray spectrometry (EDX) and atomic force microscopy (AFM) analysis. The effect of different concentrations of glycidyl POSS-GO (PG) in membrane matrix on separation performance and antifouling property of blended membranes was investigated by contact angle measurement, pure water flux, Na2SO4, Pb(NO3)2, CrSO4 and Cu(NO3)2 rejection and flux recovery ratio. The blended PEI/PG membranes showed significant separation performance and antifouling properties compared with neat PEI and PEI/GO membranes. The highest pure water flux measured 74.77 (L/m2·h) for the blended membrane with 0.001 wt% of PG whereas it was 51.06 (L/m2·h) for the PEI/GO membrane and 17.63 (L/m2·h) for pristine membrane at 4.5 bar pressure. The blended PEI/PG membranes showed outstanding Na2SO4 and Pb(NO3)2, CrSO4, and Cu(NO3)2 rejection compared to blended PEI/GO membranes and neat PEI ones. Furthermore, the highest flux recover ratio (FRR) value was obtained (96%) for the blended [PEI/0.1 %wt PG] membrane whereas FRR was (40%) for PEI/GO and (33%) for the neat PEI membranes.