A heating furnace for heating an annular component, includes a furnace body, a heat medium driving component, a support part, a guide component, and a hollow cylinder. Part of the heat medium is ejected to the outer circumferential surface of the annular component through the guide part, and part of the heat medium flows through the inner channel of the hollow cylinder, and be ejected to the inner circumferential surface of the bearing via the second heat medium channel arranged on the hollow cylinder to heat the inner circumferential surface of the bearing. In this way, the hollow cylinder plays a role of distributing the gas to some extent, and as the upper end of the hollow cylinder is a sealed structure, the flowing gas is all converted into effective heat exchange gas flow and restricted to a heat exchange space on the bearing surface.