We successfully synthesized PVC-g-P([Ebim][Tf2N]) by utilizing atom-transfer radical polymerization (ATRP) for the preparation of polymer/Cu nanocomposite. When Cu flakes were stirred in PVC-g-P([Ebim][Tf2N]) without any additives, Cu nanopartides were stably generated to form the polymer/Cu nanocomposite. The dissociation of nanopartides from the flakes is attributable to the strong interaction between cations of PVC-g-P([Ebim][Tf2N]) and the metal surface. The generated Cu nanoparticles exhibited a polydisperse distribution, as confirmed by UV-vis spectral analysis and transmission electron microscopy (TEM) imaging. Furthermore, the surface state of the Cu nanoparticles was investigated by X-ray photoelectron spectroscopy (XPS), which was confirmed by a decrease in binding energy.