Relaxor ferroelectrics are the most promising materials for dielectric capacitors because of their rapid charge/discharge capability and outstanding thermal stability. However, to satisfy the advanced requirements of pulsed power capacitors, these electrical properties need substantial enhancement. In this paper, the breakdown strength of the ceramic is improved by constructing a barrier layer with CaTiO3 filler in the system, and it optimizes the ceramic's electrical characteristics by regulating the size of the filler. Subsequently, the relaxor behavior is enhanced, achieving a dispersion coefficient of 1.75, and the band gap (Eg) increases to 2.67 eV, raising the breakdown strength from 140 kV/cm to 220 kV/cm, maintaining relatively good temperature stability. The recoverable energy storage density (Wrec) achieved is 0.73 J/cm3 using CaTiO3 with dimensions of 5.80×2.10×2.20 μm. This paper proposes a novel strategy to boost the electrical performance of dielectric materials.