||Conventional heat radiating materials are produced by simply dispersing ceramic fillers in a polymer matrix and form a heat transfer path above 50 wt% of ceramic filler, which decreases the tensile strength of heat radiating material due to the high content of ceramic fillers. In this study, amphiphilic diblock copolymers which can selectively disperse aluminum oxide(Al2O3) as a thermally conductive filler were used. If Al2O3 is selectively dispersed through interaction with a specific block in a phase separated block copolymer, Al2O3 is concentrated in a specific block. Also it forms a 3D network heat transfer path by adding small amount of carbon nanotubes(CNT) to act as a heat transfer bridge between Al2O3. Therefore, the electrical insulating heat radiating material prepared in this study can form a high effective heat transfer path, which leads to high thermal conductivity even at low ceramic filler content.