The invention discloses a polycrystalline silicon reduction furnace body. 3-5 layers of metal thermal baffles are arranged in the furnace body; and the multiple layers of metal thermal baffles are fixedly connected together by virtue of stainless steel bolts and are fixed to the inner wall surface of the furnace body in a bolted connection mode. The thermal baffles are made of stainless steel, the shapes of the thermal baffles are consistent with the inner wall of the furnace body, and the interlayer of the thermal baffles is communicated with the inner cavity of the furnace body. According to the polycrystalline silicon reduction furnace body disclosed by the invention, the multiple layers of metal thermal baffles cover polycrystalline silicon bars, so that the heat loss can be greatly reduced, the utilization rate of heat energy in the furnace body is improved, the problem that energy waste is caused because the inner wall of the conventional furnace body is difficult to polish and the polishing effect is poor is solved, and the production cost of the polycrystalline silicon is reduced by virtue of low electric energy and an easily operated technology.