The invention relates to an optical fiber drawing furnace comprising a furnace body, a heating element, a heat preservation element, a middle casing pipe, a flow guide pipe, an extension pipe and a furnace top gaseous disc. The optical fiber drawing furnace is characterized by further comprising a lantern ring, an elastic graphite ring and a gas guide disc. The gas guide disc is mounted on the furnace top gaseous disc. The elastic graphite ring is mounted on a hollow ring plate. The lantern ring is arranged between the flow guide pipe and the extension pipe. A plurality of first air inlet holes can be formed in the side wall of the extension tube at the upper end of the lantern ring. The optical fiber drawing furnace has the advantages of being applicable to drawing prefabricated bars in large diameter and optical fiber prefabricated bars with large diameter fluctuation, meanwhile ensuring that graphite dust has less possibility of being adhered to the prefabricated bars, and effectively controlling the air flow state in the drawing furnace.