The V_(Pb) defect structures in PbWO_4 are studied within the framework of full-relativistic density functional theory.Using the conjugate gradient method,the geometrical construction of the ions around the lead vacancy is optimized.The optimized ion coordinates around lead vacancy have been obtained.The result indicated that these next nearest positive ions Pb~(2+) and W~(6+) will shift towards V~(2-)_(Pb) and these nearest negative ions O~(2-) will shift outwards.This will decrease the electrical negativity on V~(2-)_(Pb) site.