Heavy metals like copper and lead are one of the major contaminants in wastewater. In this study, the functionalized POSS nanoparticles were used to modification of PEI-based nanofiltration membranes for Pb+2 and Cu+2 ions removal from water. The L-cysteine was applied to functionalization of glycidyl POSS. The FTIR, and FESEM were applied in functionalized nanoparticles and membrane characterization. The pure water flux increased considerably from 17.63 (L/m2h) for PEI membrane to 95 (L/m2h) for the modified membrane containing 1 wt.% functionalized POSS. The Pb+2and Cu+2 rejections measured 85and 86% for membrane with 1 wt.% functionalized-POSS whereas they were 44 and 40% for the neat membrane. The results showed high capacity for blended nanocomposite membranes to lead and copper removal from water compared with other reported ones.