In this study, we reported a new BaTiO3-Na0.5Bi0.5TiO3-Nb2O5-Mn2O3/Fe2O3/Co3O4/In2O3 X8R system with high dielectric constant (>2100) at room temperature. The impacts of oxygen vacancy (V-o(center dot center dot)) on dielectric, electrical conductivity, and ferroelectric properties were systematically studied. The Curie point is largely depended on the V-o(center dot center dot) concentration, which can be confirmed by the dielectric behavior and A(1g) octahedral breathing modes in Raman spectrum. In addition, the activation energy of V-o(center dot center dot) diffusion is greatly reduced with the increase in V-o(center dot center dot) concentration. It was found that the remnant polarization and coercive field were both decreased with increasing V-o(center dot center dot) concentration, due to the facilitated defect dipoles reorientation and domain switching.