A method of realizing ultraviolet (UV) laser induced domain reverse in LiNbO3 crystals is investigated experimentally. With a certain external electric field, a sample of LiNbO3 crystal is illuminated by a UV laser beam of 365 nm wavelength. For the reason that the coercive field of the crystal is decreased by exposure of UV light, it is only the illuminated region whose domain is reversed. The results prove that this method can be used to realize the fabrication of periodically poled LiNbO3 crystals, and it will become an effective solution to smaller periods.