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 the 532 nm wavelength laser radiation with intensity up to 15 MW/cm2. Several evidences demonstrated the improvement of the cryatallinity of the CdS thin film after the laser radiation. The improvement was proved by optical methods: the appearance of photoluminescence band at ~2.520 eV, which is attributed to free exciton emission; the appearance of “spike” in the reflection spectrum at ~2.573 eV between upper and lower polariton branches and the increase of the 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 CdS crystals after laser radiation takes place, which was proved by X-Ray diffraction pattern and using the Scherrer equation.