The nc-Ge/a-Si multilayer structures were fabricated by ion beam sputtering technique on silicon substrates at temperature of 400 °C. Raman scattering spectroscopy, atomic force microscopy (AFM) and room temperature photoluminescence were used to characterize the structure and optical property of the samples. It was found that the nc-Ge/a-Si multilayer sample can be obtained when the Ge sublayer is 3 nm. The room temperature photoluminescence was observed and the luminescent peak is located at 685 nm. Compared with the a-Ge/a-Si film, the intensity of PL of the nc-Ge/a-Si multilayer film becomes stronger due to the higher volume fraction of crystallized component.