The　packaging　insulation　of　power　electronic　devices　works　in　high-frequency,　high-voltage,　and　high-temperature　environments,　which　suffers　from　electrical　tree　aging　and　seriously　restricts　the　reliable　operation　of　power　electronic　devices.　In　this　paper,　WZ　breakdown　model　is　used　and　the　tree　growing　and　fractal　dimension　characteristics　with　different　sheets　size　are　simulated.　In　addition,　electrical　tree　initiation　and　growing　characteristics　of　BN/epoxy　resin　composites　are　observed　and　studied　under　high-frequency　voltage.　Results　show　that　with　the　increasing　sheet　size,　tree　initiation　voltage　increases　first　and　then　decreases.　From　the　simulation　and　experimental　results,　after　adding　two-dimensional　sheet,　electrical　tree　tends　to　be　more　bifurcated,　and　as　the　sheet　size　increases,　the　growing　rate　decreases,　the　fractal　dimension　of　tree　increase　correspondingly.　It　is　believed　that　by　introducing　BN　sheet　into　the　matrix,　the　barrier　effects　and　the　forming　deep　trap　both　make　electrical　tree　difficult　to　initiate　and　grow.　The　above　researches　could　provide　a　solution　to　the　regulation　of　electrical　tree　aging　performance　in　the　insulation　layer　of　power　electronic　devices.　©　2022