The oxidation states of Ge nanoparticles in the surface layer of Ge/Si film were studied by X-ray photoelectron spectroscopy. New features appeared at the high binding energy side of the XPS Ge 3d peak when samples were annealedin atmosphere, which were caused by the large interfacial area between the Ge and Si nanoparticles, as well as by the change in environment of the Ge nanoparticles and the oxidation states of Ge and Si.