Vacuum heating separation is one of the methods for removing insulation oil from used pole transformers. In this method, the insulation oil and PCBs are removed from the pole transformers by vaporizing them under vacuum at 200degreesC, and a high removal performance is achieved without deterioration of the insulation oil, PCBs and pole transformers. However, a long heating time is required to detoxify the pole transformers, because they are heated by radiative heat transfer under vacuum. The purpose of this study is to reduce the heating time of the vacuum heating separation method by means of heat transfer numerical simulation. The simulation results clarified the influences of operating conditions such as the number of plates, pressure in the furnace, heating temperature and heating rate on the heating time of the method.