Flexible　dielectrics　have　been　the　major　enabler　for　a　number　of　applications　in　advanced　electronic　and　electrical　power　systems.　As　an　important　flexible　dielectric　material,　polymer　composites　are　promising　in　raising　the　poor　dielectric　properties　of　neat　polymer　of　current　use.　In　this　study,　a　class　of　topological-structure　modulated　multilayer　composites　comprising　a　percolation　layer　(FeTiNbO6[FTN]/polyvinylidenefluoride　[PVDF])　intercalated　between　two　insulating　layers　(PVDF　or　BaTiO3[BT]/PVDF)　are　assembled　into　sandwich　structures　by　a　facile　hot-pressing　method.　For　the　prepared　sandwich　structure,　FTN/PVDF　film　acts　as　a　semiconductive　layer　to　raise　dielectric　permittivity,　while　two　insulating　layers　at　top　and　bottom　of　composite　are　used　to　suppress　conductivity　and　dielectric　loss.　Resulted　from　the　unique　performances　of　the　FTN/PVDF　film　and　strong　interfacial　polarization,　the　sandwich　composite　possesses　improved　dielectric　and　insulation　properties.　Moreover,　compared　with　FTN/PVDF,　the　BT20-FTN40-BT20　has　lower　dielectric　loss　and　higher　insulation　properties,　and　after　poling　at　20　kV/mm　for　6　h,　it　exhibits　excellent　vibration　energy　harvesting　properties　in　cantilever　mode.　Thus,　a　piezoelectric　energy　harvester　constructed　from　this　sandwich　composite　can　be　used　for　self-driving　wireless　sensors.　POLYM.　COMPOS.,　40:E570-E578,　2019.　(c)　2018　Society　of　Plastics　Engineers