With the advancement of power electronics technology towards multifunctionality

integration

and miniaturization

it is difficult for traditional dielectric materials to meet the demands of high energy density and the reduction of device size and weight in power electronic applications. Polymer-based nanocomposite dielectric materials with high energy storage density have attracted significant attention due to their superior processability

favorable design flexibility

and excellent dielectric properties. This review first provides a brief introduction of polymer nanocomposite dielectric materials and their interfacial characteristics

and then systematically summarizes recent strategies for constructing high energy storage density polymer nanocomposite dielectric systems

focusing on approaches such as low-content filler incorporation

core-shell structured (modified) filler integration

polymer dielectric surface modification

and multilayered structure assembly. Finally

the review addresses the current challenges associated with polymer nanocomposite dielectric materials and offers insights into their potential future developments.