Abstract: The use of industrial by-product gas combustion for power generation or heat supply can effectively improve energy utilization. Some of the by-product gases are characterized by high water content, low calorific value, and ammonia content, and thereby problems, such as unstable combustion, low fuel burnout rate, and high NO_x emission, exist in the combustion utilization of the by-product gases. Aiming at the above problems, this study firstly carries out reaction kinetic simulation and obtains the combustion and pollutant characteristics of typical ultra-low specific energy high-humidity ammonia-containing by-product gas (the off-gas of carbon black furnace). The effects of flue gas recirculation and air staging on NO_x formation in the process of off-gas combustion are investigated. A technical scheme based on multiple re-circulations of high-temperature flue gas combined with staged combustion is proposed and validated in industrial-scale applications. The results show that the use of multiple re-circulations of high-temperature flue gas to heat the reactants significantly improves the flame propagation speed, thereby making the flame more stable. The optimized staged combustion scheme effectively inhibits the formation of fuel-NO_x. The results of industrial-scale experiments present that the combustion stability and fuel burnout rate are effectively improved by using the proposed combustion organization method. The CO emission concentration is lower than 50 mg/N·m³, and the NO_x emission is reduced by 300~400 mg/N·m³. The adoption of combustion stabilization scheme of the multiple high-temperature flue gas internal circulation integrated with the staged combustion is capable of effectively solving the problem of combustion organization of ultra-low specific energy and high-humidity ammonium-containing gases.