Epoxy　resin　(EP)　has　been　used　as　insulating　material　in　power　electronic　transformer　(PET),　while　low　thermal　conductivity　of　EP　limits　the　heat　dissipation　efficiency　of　PET.　Role　of　Micro-nano　hexagonal　boron　nitride　coordination　on　thermal　conductivity　and　breakdown　strength　of　epoxy　composites　was　explored.　A　thermal　conductivity　of　0.544　W/(m·K)　was　obtained　for　10　wt%　BN/EP　micro　composites,　increased　by　149.5%　compared　with　pristine　epoxy.　In　addition,　the　specimen　with　a　dual　doping　of　10　wt%　h-BN　and　5　wt%　nano　filler　exhibited　both　improved　thermal　conductivity　of　0.527　W/(m·K)　and　breakdown　strength　of　118.3　kV/mm.　It　is　found　that　micro-BN　could　effectively　increase　the　thermal　conductivity　since　efficient　heat　transform　path　would　be　built　inside　epoxy　matrix.　Meanwhile,　nano-BN　would　bring　in　independent　interfacial　regions　that　capture　carriers　at　low　filler　content.　Based　on　the　coordination　of　micro-nano　particles,　the　thermal　conductivity　and　breakdown　strength　can　thus　be　enhanced　simultaneously.　©　2020　IEEE.