Low density polyethylene (LDPE) coated lead monoxide (PbO) nanopowder was fabricated by using in situ high energy wet ball milling. Degrees of pulverization of wet milled PbO together with LDPE and cyclohexane were analyzed by means of PSA and SEM. PbO powder could-be,pulverized to similar to 100 nm for 1 h milling while the surfaces of the powder particles were modified with LDPE simultaneously. Surface modification by elemental interdiffusion Of PbO and carbon on the particulate boundary was confirmed by TEM/EDX. High density polyethylene (HDPE) nanocomposites were also prepared by dispersing micro- and nano. PbO/LDPE powders using a polymer melting mixer. Dispersion and adhesion of PbO/LDPE nanoparticles in or with the polymer matrix were homogeneous and strong respectively according to the SEM images. as well as the FTIR spectra, while the HDPE nanocomposites show higher mechanical properties than those for micro-PbO powder dispersed ones.