Blast furnace gas presents high CO₂ content, and the capture and resource utilization of blast furnace gas cannot only help to reduce carbon emissions in the iron and steel industry, but also increase the calorific value of blast furnace gas. The ammonia is employed as an absorbent to capture CO₂ (ammonia method), and the effects of ammonia concentration, gas-liquid ratio, reaction temperature and CO₂ volume fraction of blast furnace gas on O₂ emission reduction are carried out. The results show that increasing the concentration of ammonia can significantly enhance the chemical adsorption of CO₂ by ammonia, increasing the temperature of ammonia will accelerate the absorption rate of CO₂, and increasing the liquid-gas ratio can make the contact between the liquid in the spray tower and CO₂ more fully under the action of the spraying device, so increasing ammonia concentration, temperature and gas-liquid ratio can lead to the increase of CO₂ removal rate. With the continuous introduction of O₂, the ratio of the amount of NH₃ to CO₂ decreases, and the reaction impetus decreases, which are not conducive to O₂ absorption. When the concentration of ammonia is 1.5 mol/L, the gas-liquid ratio is 1.3 L/m³, the reaction temperature is 20 ℃, and the O₂ volume fraction in blast furnace gas is 15%, the removal rate of ammonia method can reach 90.73%. The absorption solution is evaporated to obtain the white crystal product ammonium bicarbonate (NH₄HCO₃).