A possibility to improve the quality of polycrystalline CdS thin film by Nd:YAG laser irradiation was shown. The CdS thin film was prepared by closed space sublimation method on ITO/glass structure and irradiated by Nd:YAG laser with intensity up to 15 MW/cm2. Several evidences demonstrated the improvement of the optical properties of the CdS thin film after the laser radiation: appearance of photoluminescence band at ~2.530 eV, which is attributed to bound exciton emission; appearance of “spike” in the reflection spectrum at ~2.573 eV between upper and lower polariton branches and the increase intensity of LO phonon line at 305 cm-1 about 3 times in Raman back scattering spectra. Moreover, the increase by 20% of the size of crystals in CdS after laser radiation takes place, which was proved by using X-Ray diffraction analysis.