A 532nm Nd:YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of Nd:YAG laser to low-temperature polycrystalline Si technology. In this study, we aim at enhancing uniformity as well as crystallinity. In order to achieve the goal, a new optical system called as a diffusing system was used to enhance the uniformity of irradiating beam profile, consequently improving the quality of crystallized microstructures. Optimal processing parameters for high crystallinity and uniformity were developed by design of experiments (DOE). To investigate crystallinity and uniformity, Raman spectroscopy and optical microscopy were utilized. Therefore, the effectiveness of Nd:YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.