Dielectric nanocomposites have attracted extensive attention since the potential application in the field of energy storage. Nevertheless, it is still a challenge to fabricate dielectric nanocomposites with high discharged energy density. Herein, lead-free bismuth sodium titanate (BNT) particles are used as filler in nanocomposite due to their outstanding dielectric properties. In this paper, BNT nanoparticles decorated by dopamine were employed to fabricate BNT@Dopa/poly(vinylidene fluoride) (PVDF) nanocomposites. Dielectric properties and energy storage performance of nanocomposites with BNT nanoparticles enhanced significantly. The maximum dielectric constant (epsilon(r)) of nanocomposites with BNT@Dopa nanoparticles was 14.15 at the frequency of 1 kHz. The discharged energy density (U-dis) of nanocomposites with 3 vol% BNT@Dopa nanoparticles reached 13.09 J/cm(3) at 430 kV/mm. The energy efficiency (eta) of nanocomposites at 40 degrees C remained 53.62% at the electric field of 350 kV/mm. The nanocomposite with BNT@Dopa nanoparticles performed excellent fatigue endurance after 10(6) cycles. These results offer a practicable way to fabricate nanocomposites with high energy density.