BaTiO3/polyvinylidene　fluoride　(BT/PVDF)　is　the　extensive　reported　composite　material　for　application　in　modern　electric　devices.　However,　there　still　exists　some　obstacles　prohibiting　the　further　improvement　of　dielectric　performance,　such　as　poor　interfacial　compatibility　and　low　dielectric　constant.　Therefore,　in　depth　study　of　the　size　dependent　polarization　and　surface　modification　of　BT　particle　is　of　technological　importance　in　developing　high　performance　BT/PVDF　composites.　Here,　a　facile　molten-salt　synthetic　method　has　been　applied　to　prepare　different　grain　sized　BT　particles　through　tailoring　the　calcination　temperature.　The　size　dependent　spontaneous　polarization　of　BT　particle　was　thoroughly　investigated　by　theoretical　calculation　based　on　powder　X-ray　diffraction　Rietveld　refinement　data.　The　results　revealed　that　600　nm　sized　BT　particles　possess　the　strong　polarization,　ascribing　to　the　ferroelectric　size　effect.　Furthermore,　the　surface　of　optimal　BT　particles　has　been　modified　by　water-soluble　polyvinylpriolidone　(PVP)　agent,　and　the　coated　particles　exhibited　fine　core-shell　structure　and　homogeneous　dispersion　in　the　PVDF　matrix.　The　dielectric　constant　of　the　resulted　composites　increased　significantly,　especially,　the　prepared　composite　with　40　vol　%　BT　loading　exhibited　the　largest　dielectric　constant　(65,　25　degrees　C,　1　kHz)　compared　with　the　literature　values　of　BT/PVDF　at　the　same　concentration　of　filler.　Moreover,　the　energy　storage　density　of　the　composites　with　tailored　structure　was　largely　enhanced　at　the　low　electric　field,　showing　promising　application　as　dielectric　material　in　energy　storage　device.　Our　work　suggested　that　introduction　of　strong　polarized　ferroelectric　particles　with　optimal　size　and　construction　of　core-shell　structured　coated　fillers　by　PVP　in　the　PVDF　matrix　are　efficacious　in　improving　dielectric　performance　of　composites.　The　demonstrated　approach　can　also　be　applied　to　the　design　and　preparation　of　other　polymers-based　nanocomposites　filled　with　ferroelectric　particles　to　achieve　desirable　dielectric　properties.