The influence of ion source bias voltage and deposition temperature on the optical properties and crystallization properties of zinc sulfide films is studied. The ZnS film is prepared on K9 glass substrate by electron beam evaporation technology. A spectrophotometer is used to test the optical properties of the film. The change rules of the refractive index and extinction coefficient of the film are obtained by the spectral inversion method. The crystal state of the film is tested by X-ray diffraction method. As the bias of the ion source increases, the refractive index of the film gradually decreases, but the change range is not large. When the ion source bias voltage is 160 V, the refractive index of the film at a wavelength of 1000 nm reaches a minimum value of 2.210. After the heating is turned on, the refractive index of the film increases significantly. As the deposition temperature increases, the refractive index of the film gradually increases. When the deposition temperature is 210 ℃, the refractive index of the film at a wavelength of 1000 nm is 2.312 at the maximum. The extinction coefficients of the films prepared under the two process states are very small. The preferred orientation of film growth during ion-assisted deposition is the (220) crystal orientation. The preferred orientation of the film deposited under the heating state of the substrate is the (111) crystal orientation. As the ion source bias increases, the diffraction intensity of the thin film (220) peak decreases. The higher the deposition temperature is, the greater the diffraction intensity of the thin film (111) peak. Through the research in this paper, it is found that the optical characteristics of the zinc sulfide film are more sensitive to changes in deposition temperature. Both the ion source bias and the change in deposition temperature can significantly affect the crystalline state of the zinc sulfide film.