Zinc sulfide thin films were deposited on optical glass substrates by using chemical bath deposition (CBD) technique that contain solutions of thiourea, zinc acetate, ammonia and sodium citrate. The deposition time were varied from 18 hours to 39 hours. SEM, XRD, and UV-Vis-NIR were used to characterize the sample which shows that the films are thicker and the grains sizes are bigger as the deposition time increases. X-ray diffraction (XRD) pattern prove that ZnS thin films are in disordered since it does not revealing any peaks and the surface of ZnS thin films are amorphous. UV-Vis spectra showed that the deposited ZnS thin films have more than 100% transmittance in the visible region and direct band gap of deposited films are in range of 2.45 eV to 3.53 eV. Time increasing of deposition will slightly decrease the transmittance of the film.