The crystal and optical properties of ZnS optical coatings deposited at different substrate temperatures are studied in this paper. It is indicated that the substrate temperature has an evident effect on the properties of ZnS films. The XRD varies with the temperature. With the increase of the temperature, the XRD of ZnS film exhibits an obvious (111) orientation. At the same time, ZnS films have different stabilities at different substrate temperatures. At 115 ℃ and 155 ℃, the stability gets worse but at 190 ℃ and 230 ℃, it gets better. The variation of the substrate temperature has also effect on the optical properties of ZnS film, such as optical constants and deposition coefficient. At higher temperatures (190 ℃ and 230 ℃), the refractive index is higher than at lower temperatures (115 ℃ and 155 ℃). But the deposition coefficient gets smaller. Optical constants of ZnS films are calculated at different temperature.