Abstract: The flue gas protecting roller hearth furnace is a heat treatment furnace in which the flue gas is injected into its hearth to serve as a protective gas so as to make the atmosphere in the furnace form a micro oxygen environment. An ordinary roller hearth furnace was successfully modified in Pangang Group Chengdu Steel & Vanadium Co.,Ltd.,Jintang branch in July of 2011 with the expected effect achieved. The modification of the ordinary roller hearth heat treatment furnace to the flue gas protecting roller hearth furnace is briefly analyzed in such aspects as furnace construction,gas circulation system,cooling water system,oxygen content detection and electrical and instrument control system.