Nanocrystalline ZnS thin films are prepared on glass substrates under various deposition conditions (radio frequency power, and sputtering pressure) using radio frequency magnetron sputtering at room temperature. Through optimization of deposition process, very thin and uniform ZnS layer was deposited to minimize the light blocking effect in short wavelength region. This paper investigates the influence of ZnS buffer layer by magnetron sputtering,and analyses structure,surface topography,and optical properties of ZnS films by using X-ray diffraction (XRD), UV-spectroscopy measurements and scanning electronic microscope (SEM) analysis techniques. Findings show that the high-quality ZnS thin films with a good crystallinity and optical properties, which is zinc blende cubic structure with a preferred orientation, can be grown by sputtering at 300W and 0.6Pa. The films exhibit the optical transparency as high as 80% in the visible region, and the resultant ZnS thin films have a high crystallinity, low defect concentration and good optical properties with the band gap of 3.50eV.