LiNbO3 crystals doped with different amount of MgO have been produced using vapor transport equilibration technique. The poling characteristics of the crystals with different MgO doping levels have been investigated. The switching field and the spontaneous polarization Ps of the crystals were expressed as functions of crystal stoichiometry and Mg content. The switching field for the domain reversal in the near stoichiometric crystal with ［Li］/［Nb］=0.973 doped with 2.0mol.% MgO was 1.8kV/mm. This is about one twelfth of the switching field for the congruent crystal, and the pattern of the periodic domain in the crystal is better than in the congruent and stoichiometric crystal.