Abstract: Industrial flue gas from iron and steel mills contains a large number of toxic gases such as carbon monoxide, nitrogen oxide, sulphur dioxide and other toxic gases, as well as oxygen, water vapour and other components that are toxic to the catalyst. CO−SCR (CO−selective catalytic reduction) technology is developed to remove both CO and NO simultaneously through the use of catalysts and to ensure high catalyst activity at flue gas temperatures and in toxic atmospheres. Iron-based catalysts used for the CO−SCR reaction in recent years are systematically discussed. By introducing the properties and activities of catalysts with different morphological structures, the advantages and disadvantages of various iron-based catalysts in the CO−SCR reaction are objectively summarized in terms of methods for increasing catalyst defects, modification of catalysts by noble metal doping, and the influence of supports on catalyst properties. Subsequently, the structure-activity relationship between CO−SCR reaction performance and different iron-based catalysts is analyzed, and the CO−SCR reaction mechanism under the action of iron-based catalysts and their modified counterparts is explored. Finally, by analyzing the actual flue gas conditions and the application conditions of iron-based catalysts in the absence or low oxygen concentration, the rational development of iron-based catalysts, the enhancement of the activity of low-temperature CO−SCR and the improvement of the ability to prevent oxygen poisoning are prospected.