Polycrystalline ZnO films were prepared on glass wafer using Zn targets by radio frequency(RF) reactive sputtering technique under different deposition conditions. X - ray diffraction (XRD) and optical transmittance spectrum were employed to analyze the structure and optical character of the films.The strain and stress in films, as well as the packing density are calculated in terms of refractive index of films measured with an elliptic polarization analyzer.It is the deposition conditions that have great effects on the structural and optical properties of ZnO films.Under the optimal conditions,the only evident peak in XRD spectrum was (002) peak with the full width at half maximum (FWHM) of 0.20°showing the grain size of 42.8 nm.The packing density,the stress in (002) plane and the average optical transmittance in the visible region were about 97%,-1.06×109 N/m2 and 92%, respectively.