Abstract: Based on the heating furnace in an iron and steel works, the gas utilization efficiency was analyzed under conditions of different types of combustion through the heat balance of the furnace. The flame stability, intensity of thermal load and reasonable replacement of improper fuel gas were taken into account to investigate the fuel gas interchangeability of industrial heating furnaces and boilers. And the feasibility of the interchangeability between the gases mixing coke oven gas with blast furnace gas of different thermal values and pure coke oven gas was investigated. A conclusion was drawn that the mixed gas was available to replace coke oven gas to meet the requirements for production process, energy saving and alleviating environment pollution if the air consumption coefficient n=1.05, the ratio of coke oven gas to mixed gas α ≥ 0.3 and the thermal value of mixed gas > 7860 kJ/m³.