The defects associated with lead vacancies (VPb) in lead tungstate crystals (PbWO4) are investigated by the relativistic self-consistent discrete variational embedded cluster method. We focus on the density of states and the effect of VPb on surroundings. The results show that the existence of VPb can diminish the bandwidth of WO42- group,however, it can neither produce O- and Pb3+ ions nor result in absorptions at 350 and 420 nm. The charge balance of VPb may be evenly compensated by the surrounding oxygen ions.