Electronic devices and main boards have a tendency to increase the internal heat radiation performance for excellent thermal conductive materials, as necessary for miniaturization. In this study, Nano-thermal grease was prepared by mixing copper Nano-powder into thermal grease, one of the types of thermal conductive materials, by volume percentage. The thermal conductivity was measured and analyzed. As a result, the thermal conductivity was excellent in the order of Case 5, Case 4, Case 3, Case 2, Case 1. However, when the copper powder of Case 5 or more samples was added, stirring did not proceed smoothly due to the high viscosity. This is considered to be because the maximum capacity of the thermal grease was exceeded.