Three-dimensional　(3D)　thermally　conductive　boron　nitride　(BN)/polymer　composites　show　significant　potential　in　the　field　of　thermal　management.　This　review　surveys　current　advances　and　discusses　the　thermal　conductivity　mechanisms　of　BN/polymer　composites　and　the　critical　factors　influencing　their　performance.　A　thorough　introduction　to　the　construction　methods　of　3D　thermally　conductive　BN/polymer　composites　is　provided,　along　with　an　objective　discussion　of　their　advantages　and　disadvantages.　Notably,　this　review　specifically　highlights　the　effects　of　3D　thermally　conductive　networks　on　phonon　transmission,　interfacial　thermal　resistance,　and　thermal　conductivity,　as　well　as　their　interactions,　and　points　out　recent　innovative　trends　in　constructing　3D　thermal　composites　by　integrating　BN　with　other　dimensional　fillers　(0D,　1D,　and　2D　fillers).　These　approaches　demonstrate　promising　strategies　for　optimizing　thermal　management　by　leveraging　the　unique　advantages　of　each　dimensional　filler.　The　review　concludes　with　a　summary　and　outlook　on　the　development　of　3D　thermally　conductive　BN/polymer　composites.　This　aims　to　provide　theoretical　analysis,　advance　practical　applications,　and　enhance　next-generation　thermal　management　systems.