Ge clusters and their assembled nanofilms were prepared by means of the inert-gas condensation method and analyzed by electron microscope and UV-visible photo spectrophotometry.Two kinds of nanostructured films assembled from Ge clusters covered with oxide shells were obtained with different microstructure and morphology.Spectrophotometric measurements were performed for these samples in ultraviolet,visible and near-IR region,and show obvious blue-shift of the optical band gap as large as 1.0-2.0 eV in comparison with the bulk,which can be explained by quantum confined effect.