The invention relates to a heating system of a tempering device. The heating system comprises a heating cavity. The inner side face of the heating cavity is provided with a first heating device. The heating cavity comprises a detachable bottom face plate and a first side face plate. The inner surface of the bottom face plate is provided with a second heating device. The inner surface of the firstside face plate is provided with a third heating device. The first heating device, the second heating device and the third heating device all comprise heating modules and are all provided with fixed racks connected with the heating modules. Each heating module comprises ceramic tubes and heating wires wound around the ceramic tubes. The heating system of the tempering device has the following technical effects that the temperature uniformity in a furnace is effectively improved through the fixed support structure; the whole bottom plate is arranged for heating, the heat efficiency is further improved, and energy consumption is reduced.