In this research we prepared PbS thin films by Spray pyrolysis method on a glass substrates and we study its optical properties . The result of (X-Ray ) diffraction showed that thin films have a polycrystalline structure , The relation of The Absorption and The transmission as a function of Photon Energy for the PbS films had been studied , The optical energy gap of the direct allowed transitions for the PbS is (0.41 eV). The optical Absorption coefficient , extinction coefficient , Refractive Index, Reflection of Coefficient and Extinction Coefficient as a function of Photon Energy have been studied.