The influence of polarization state on laser-induced domain nucleation in Mg-doped and Hf-doped LiNbO3 is investigated. The phase distributions during laser-induced domain nucleation are reconstructed by digital holographic interferometry. The comparisons of nucleation field with different polarization states including linear polarization, circular polarization and elliptical polarization are performed. The generated space-charge field along z direction is thought to be important mechanism. Not only the essential information for the future optimization of laser-induced domain engineering is provided, but also the new experimental evidences for the future mechanism investigation of laser-induced domain nucleation are supplied.