Surface functionalization of zinc oxide (ZnO) nanoparticles was performed by glycidyl POSS. The synthesized nanoparticles were applied to prepare polyether-imide based-nanofiltration membranes by phase inversion method. The characterizations were done by FESEM, EDX and AFM analysis. The effect of different concentrations of POSS-ZnO (PZ) nanoparticles was investigated to evaluate the separation performance of prepared membranes by contact angle measurement, pure water flux (PWF), rejection of aqueous solutions including Na2SO4, Pb(NO3)2, Cu(NO3)2 and flux recovery ratio (FRR%). The prepared PEI/PZ membranes showed significant separation performance and antifouling properties compared with neat PEI and PEI/ZnO membranes. The highest pure water flux (42.4 L/m2h) was revealed for M1-PZ in 0.001 wt% of PZ nanoparticles, whereas that was 17 (L/m2h) for neat membrane and 12-18 (L/m2h) for PEI/ZnO, respectively. Also, salt rejection was low for blended PEI/ZnO membranes. By incorporation of PZ into the PEI, Na2SO4, and Pb (NO3)2 rejection improved to 83% and 59%, respectively. Moreover, the M3-PZ showed the best separation performance for Cu (NO3)2 with the rejection of 67%. The highest antifouling properties were obtained for M4-PZ with FRR% of 59%, which is significant compared with 15% for PEI/ZnO and 30% for neat PEI membranes.