MgxZn1-xO films(0≤x≤030) have been prepared on sap phire substrates by radio frequency magnetron sputtering at a substrate tempera ture of 80℃. Optical and structural properties of the MgxZn1-x O films were studied using transmittance and x-ray diffraction (XRD)spect ra. XRD patterns indicate that the MgxZn1-xO films have he xagonal wurtzite single-phase structure of ZnO and a preferred orientation with the c-axis perpendicular to the substrates without any significant formation o f a separated MgO phase. The c-axis lattice constant of the MgxZn1-xO films decreases gradually with increasing Mg content. Sharp absorp tion edge appeared in the transmittance spectra of the MgxZn1-x O films, the fundamental band gap of the MgxZn1-xO f ilms were estimated, which increases almost linearly from 3.32 eV at x=0 to 3.9 6 eV at x=030