The microstructures and dielectric properties of Sb2O3-doped (Ba0.7Sr0.3)Ti1.005O3 (BST) ceramics for capacitor applications prepared by conventional solid state method were investigated with variation of Sb2O3 content and different sintering process by scanning electron microscope, X-ray diffractometer and LCR measure system. It is found that with the increase of Sb2O3 addition content, (Ba0.7Sr0.3)Ti1.005O3 ceramics transform from single phase solid solution with cubic perovskite structure to multiphase compounds. And Sb3+ ions mainly occupy the A sites of perovskite structure in (Ba0.7Sr0.3)Ti1.005O3 ceramics with excessive TiO2. The abnormal grain growth accompanied by the appearance of cylindroid grains and nonuniform distribution of grain size are observed in (Ba0.7Sr0.3)Ti1.005O3 ceramics with high Sb2O3 concentration. The Curie temperature and dielectric constant maximum of (Ba0.7Sr0.3)Ti1.005O3 ceramics increase and then diminish with the increase of Sb2O3 doping content. At room temperature the dielectric properties of (Ba0.7Sr0.3)Ti1.005O3 ceramics with high Sb2O3 content can be improved by properly increasing the sintering temperature and prolonging the sintering process.