Polymer-based dielectric materials have attracted increasing attention owing to their huge potential applications in modern electronic devices. The dielectric behaviors of polymer composites are greatly determined by the distribution of fillers, thus the clarification of the relationship between the dielectric properties of the composites and the spatial distribution of fillers would be highly favorable for designing novel high-performance dielectrics. Herein, the dielectric performances of ternary composites consisting of barium titanate (BT), carbon nanotube (CNT) and poly(vinylidene fluoride) (PVDF) were investigated. For comparison, the dielectric properties of trilayer composites were also studied. The ternary composites exhibited an ultra-high dielectric constant of 7×103 @10 kHz, but a high loss tangent of 25 @10 kHz. For the trilayer composites, the BT/PVDF outer layers could restrain the development of leakage current, leading to low loss tangent (0.03 @10 kHz) and high breakdown strength. Meanwhile, the trilayer composites also achieved a high dielectric constant of 95 @10 kHz owing to the considerably enhanced polarizations at the filler/matrix and layer/layer interfaces. This research provides important sights into the relationship between the dielectric properties of the composites and the spatial distributions of fillers, which will strongly boost the exploration of high-performance dielectrics.