The effect of sulfide treatment on the electrical, structural and photoluminescent properties of ZnS films is investigated. The dependences of crystal quality and luminescence on sulfide treatment are found. The crystallinity can be enhanced while following sulfide treatment. Such an improvement indicates the reduced number of sulfur vacancies (VS) as a result of the adsorption (incorporation) of the sulfur atoms during the sulfide treatment process. A correlation between the VS density and sulfide treatment is identified for providing a guide to tune the photoluminescence spectra and p-type conductivity for ZnS samples.