In this study the physical properties such as the thermal conductivity, thermal diffusivity, porosity and density of the epoxy composites were characterized as a function of weight fraction of granite. According to the test results, addition of granite increases the thermal properties of the composites. This is due to the smaller interfacial thermal barrier at the interface between the particles and the matrix, and the easy pathway among particles, and we can say decrease of apparent porosity and increase in density because of the highest density of granite comparable with density of epoxy.