The Zn3N2 is a kind of wide band gap semiconductor and it can be converted into ptype ZnO:N after oxidation at temperatures higher than 400°C which has significant potential for electronic and optoelectronic applications. The Zn3N2 films were prepared by RF magnetron sputtering a metallic zinc target in NH3Ar mixture gases on glass substrate at room temperature. The optical transmission, optical absorption, structural property, chemical bonding states, photoluminescence were measured using a double beam spectrophotometer, Xray diffractometer (XRD), Xray Photoelectron Spectroscopy (XPS), fluorescence spectrometer. The effects of NH3 ratio on the structural and optical properties of the films were examined. XRD analysis indicates that the films are polycrystalline and have a preferred orientation of (321). The intensity of the Zn3N2 (321) peak increases with the NH3 ratio. The films prepared with the NH3 ratios of 5%~10% have low transmission values, the transparency of the films get better with the increase of the NH3 ratio. The Zn3N2 films have an indirect band gap, the optical band gap increases from 2.33 to 2.70 eV when the NH3 ratio varies from 5% to 25%. XPS analysis shows that the Zn3N2 film is easily hydrolyzed by air moisture. Photoluminescence spectrum shows two emission peaks, which are located at 437 nm and 459 nm.