In electronic and electric instruments, heat dissipation is one of the major issues that degrade performance and efficiency. Polymer material has high specific strength and modulus, and it is mainly used in electrical insulation materials due to easy processability and light in weight with great flexibility but has low thermal conductivity. This paper examines the recent developments in highly thermal conductive epoxy-based polymer composites. First, the composite materials, with applications, are briefly introduced. Second, the thermally conductive polymer types with their thermal conductivity are summarized. Third, the thermal and electric properties of different boron nitride (BN) with epoxy-filled composite are listed. It also focuses on enhancement in thermal conductivity and electrical insulation, which are mainly influenced by the microstructure and amount of filler content. Some highly thermal conductive BN polymer based composites are reviewed. Fourth, various thermal conductivity measurement techniques are listed with their drawbacks. Finally, the review gives current scenario on thermal conductive polymer materials and developments needed with challenges in this area. © 2021 Society of Plastics Engineers