Polymer　based　dielectrics　with　excellent　high　electric　field　withstanding　capability　are　of　great　significance　for　enhancing　the　power　density　and　payload　efficiency　for　both　electrical　and　electronic　systems.　However,　polymer-metal　interface　is　prone　to　defect　formation,　leading　to　the　dielectric　aging　and　the　initialization　of　electrical　breakdown　failure.　A　facile　Montmorillonite　(MMT)　coating　is　self-co-assembled　on　the　surface　of　P(VDF-HFP)　high-k　film　to　form　hundreds　of　2D　nanosheets　layers　to　impede　the　charge　injection　over　the　metal-polymer　interface.　The　MMT　coating　increases　the　breakdown　strength　of　the　P(VDF-HFP)　co-polymer　film　from　405　to　452　MV/m.　The　high　field　conduction　study　reveals　a　highly　enhanced　Schottky　injection　barrier　that　blocks　the　charge　injection　from　electrodes　to　polymer　bulk,　leading　to　significantly　suppressed　charge　injection　and　conduction　loss　in　polymer.　In　addition,　the　introduction　of　MMT　layered　coating　leads　to　prominent　suppression　of　interfacial　polarization　loss,　a　phenomenon　known　as　the　blocking　capacitance,　which　would　otherwise　stem　from　the　accumulated　charges　of　polymer-metal　interface,　by　one　order　of　magnitude,　as　demonstrated　by　the　dielectric　response　analysis　by　using　the　Dissado-Hill　model　over　a　broad　range　of　temperature　and　frequency.　The　superior　charge　injection　and　interfacial　polarization　suppression　via　the　application　of　MMT　coating　impart　the　P(VDF-HFP)　co-polymer　film　with　higher　breakdown　strength,　and　provides　an　effective　approach　to　develop　high　performance　polymer　dielectrics　by　interfacial　engineering.　This　work　provides　insights　into　the　understanding　of　the　enhancement　mechanism　of　2D　coating.　©　2022