Composite films of TiO2-SiO2 have been deposited on Si(100) wafers and glass (BK7) substrates by helicon plasma sputtering at room temperature. The results of X-ray diffraction and high resolution transmission electron microscopic observation showed that all of the composite films have an amorphous structure. The observation of scanning electron microscopy exhibited that the surfaces of all of the composite films have dense smooth morphology. The refractive index and the transmittance of the composite films varied gradually in the whole composition range of the TiO2-SiO4 binary system. TiO2-SiO2 composite-films exhibited a transmittance of more than 90% compared with that of the glass (BK7) substrate. The relationship between refractive index and TiO2 content for the composite films can be described using the Lorentz-Lorenz model