||As household appliances such as mobile phones and automobiles are integrated and miniaturized, a large amount of heat is generated in the driving time. And it is important to release the heat to the outside, because heat degrades the performance of device, causes malfunctions and has a large impact on durability. Then market size of the heat-radiating materials are increasing every year. In this study, polyurethane(PU)/modified boron nitride(m-BN) composite was prepared for heat-radiating film. PU is flexible and has excellent tensile strength, also physical property can be easily controlled through the molecular design. However, owing to the PU is unstable in heat and easy to burn, its use is restricted in the field which is a risk of fire due to heat, leakage, spark etc. Then BN was modified with organo-phosphorus incorporated silane coupling agent to solve the combustion problem. Synthesis and property of PU/m-BN composite was investigated by FT-IR, DSC, TGA and LFA.