Polymer　nanodielectrics　with　high　breakdown　strength　(E-b),　high　energy　density　(U-e)　and　low　energy　loss　have　great　potential　to　be　used　as　capacitive　energy　storage　materials　of　high-voltage　film　capacitors　in　modern　electrical　and　electronic　equipment,　such　as　smart　grids,　new　energy　vehicles　and　pulse　powered　weapons.　Usually,　inorganic　nanoparticles　with　high　dielectric　constant　(epsilon(r))　are　added　into　a　high　E-b　polymer　matrix　to　achieve　simultaneously　enhanced　epsilon(r)　and　E-b,　thus　leading　to　nanodielectrics　with　high　U-e.　However,　this　strategy　was　seriously　hampered　by　the　uneven　distribution　of　electric　fields　and　inhomogeneous　microstructures　of　the　multi-phased　nanodielectrics　until　increasing　research　work　was　focused　on　interface　engineering.　Recent　progress　in　nanocomposites　suggests　that　interface　engineering　plays　a　critical　role　in　regulating　the　polarization　and　breakdown　behaviors　of　the　nanodielectrics,　such　as　balancing　epsilon(r)　and　E-b,　enhancing　U-e　and　energy　discharge　efficiency　(eta).　This　article　highlights　the　recent　advances　in　the　interface　engineering　of　polymer　nanodielectrics,　including　theoretical　models,　interface　engineering　strategies,　and　the　latest　characterization　and　fabrication　techniques　of　high　performance　nanodielectrics.　Finally,　the　challenges　and　opportunities　in　the　interface　engineering　of　the　nanodielectrics　in　film　capacitors　are　discussed　and　predicted　from　a　practical　point　of　view.