The invention discloses a heating furnace, comprising a furnace body, a plurality of midfeathers, a plurality of groups of bottom-fired combustors and a plurality of groups of radiation coil pipe units, wherein the lower part of the furnace body is provided with a radiation chamber; the midfeathers are arranged in the radiation chamber and divide the radiation chamber into a plurality of sub-radiation zones; the plurality of groups of bottom-fired combustors are separately arranged at the bottom of the furnace body and each group of bottom-fired combustors are correspondingly arranged in the sub-radiation zones of the radiation chamber; and the plurality of groups of radiation coil pipe units are separately arranged around the sub-radiation zones of the radiation chamber. The utilization rate of space in the hearth of the heating furnace is high, so enlargement of the heating furnace is realized while the occupied land area of the heating furnace is reduced, and the volumetric heat release rate of the hearth is increased.