CaTiO3 is a typical linear dielectric material with high dielectric constant, low dielectric loss, and high resistivity, which is expected as a promising candidate for the high energy storage density applications. In the previous work, an energy density of 1.5J/cm(3) was obtained in CaTiO3 ceramics, where the dielectric strength was only 435kV/cm. In fact, the intrinsic dielectric strength of CaTiO3 is predicted as high as 4.2MV/cm. Therefore, it should be a challenge issue to enhance the dielectric strength and energy storage density of CaTiO3 ceramics by optimizing the microstructures. In the present work, dense CaTiO3 ceramics with fine and uniform microstructures are prepared by spark plasma sintering, and the greatly enhanced dielectric strength (910kV/cm) and energy storage density (6.9J/cm(3)) are obtained. This can be ascribed to the improved resistivity and thermal conductivity, associated with the fine and uniform microstructures. The different post-breakdown features of CaTiO3 ceramics prepared by different process well interpret why the enhanced dielectric strength is achieved in the SPS sample. The energy storage density can be further improved to 11.8J/cm(3) by introducing the amorphous alumina thin films as the charge blocking layer, where the dielectric strength is 1188kV/cm.