In this paper, in order to optimize the zinc sulfide film, three ZnS film samples were deposited with a magnetron sputtering system on an optical glass substrate with the trade name BK7. The effect of pressure on the optical, morphological and structural properties of the film was studied. Argon gas was used for plasma generation and sputtering process. Optical constants including refractive index and extinction coefficient of the ZnS film, film thickness and band gap were calculated using PRISA software. The refractive index of the films in the visible wavelength region is on average n=1.3 and the extinction coefficient is also in the same wavelength range k=1-4. In addition, the results show that the optical constants of the ZnS films and band gaps prepared at different pressures do not differ significantly from each other. In other words, the pressure parameter is not an effective factor in determining the optical properties of the ZnS film. On the other hand, pressure has a significant effect on the deposition rate, and the results show that there must be an optimal pressure to have the maximum growth rate.