According to the different carriers of heat conduction in matter, the heat conduction mechanism of matter can be divided into: (1) electronic heat conduction; (2) phonon heat conduction; (3) photon heat conduction; (4) molecular heat conduction. The corresponding heat conduction carriers are electrons, phonons, photons and molecules in turn. Unlike metal and inorganic non-metallic materials, most polymers are saturated systems, so there are no free electrons. At the same time, the movement of molecules in polymers is relatively difficult. Therefore, their thermal conductivity is mainly through the lattice vibration, so phonon is the main heat conducting carrier of polymers; however, due to polymer chains, phonon is the main heat conducting carrier of polymers. Irregular entanglement results in low crystallinity, so there is a large amorphous part. At present, many commonly used polymer materials (such as polyvinyl chloride, cellulose, polyester, etc.) belong to crystalline or amorphous materials. Their complete molecular chains can not move freely, only the vibration of atoms, groups (or chains) occurs. Therefore, the thermal conductivity of polymers is generally unsatisfactory. At present, the preparation principle of thermal conductive polymer composites is mainly through phonon heat conduction between fillers to achieve heat conduction, which is usually achieved by adding thermal conductive fillers to the matrix.