CuS thin films were participated onto glass substrate by using chemical Bath Deposition method at (75οC) for (1hr) with different concentrations (0.03,0.05 and 0.08)M of Thiourea (TU) and Copper Chloride with molar ratio (0.01 ) have been used for solution preparation. As deposition and annealed films were studied. Non-linear absorption coefficient is measured by using Z-Scan technology and it consists of two sections. The first section is closed opening were located before detector to calculate the non-linear refractive index. Whereas the second section, were aperture located before the detector (the open aperture) is taken to calculate the non-linear absorption coefficient. Both cases are done with a CW laser with a wavelength of 650 nm and a power of 50 MW