Abstract: Polycrystalline ZnO films are prepared by RF reactive sputtering technique on Si（111）and glass wafer under different O₂ /Ar pressure ratio k and substrate temperature. X-ray diffraction technique （XRD） is employed to analyze the effect of deposition condition on structure of the films. With the increase of substrate temperature from room temperature （RT） to 400℃, the films deposited on glass appear a preferred orientation with the c-axis perpendicular to the substrate. Pressure ratio of O₂ to Ar in work gas, expressed by k（P_O2/P_Ar）, has an effect on orientation of the films, which have highly preferred orientation when k=2:3. Thegrain size is in the range of 11nm to 34nm calculated by XRD data with the Scherrer formula. It was found that under the same deposition condition, compared with the films deposited on glass, the intensity of （002） peak of the films deposited on Si（111） is weaker, however, the full width at half maximum （FWHM） of the peak hasfew change.