Polymer dielectrics are widely employed in pulsed energy storage and conversion systems due to their ultrahigh power density, fast discharge speed, and reliability. However, their low discharge energy densities pose a significant limitation for application in miniaturized and integrated devices. Here, a significantly enhanced energy storage property is achieved via incorporating Au quantum dots (QDs) into a sandwich-structured nanocomposite, where the PMMA/P(VDF-HFP) (A/F) blended polymer serves as middle layer and the P(VDF-HFP) acts as outer layer. Benefiting from the micro-capacitor and Coulomb blockade effects induced by the Au QDs, the resulting nanocomposite simultaneously achieves enhanced dielectric constant of 10.34 at 10 kHz and breakdown strength of 577.3 MV m