Abstract: Against the backdrop of China′s "Dual Carbon", CO emission reduction technologies are crucial in the sintering process. We employed Computational Fluid Dynamics (CFD) to develop separate models for the combustion of fuel particles and for sintering machines. Numerical simulations were conducted to study the effects of oxygen concentration on fuel particle combustion and the combustion process within the sintering bed. For fuel particles, increasing oxygen concentration effectively improves conditions for complete combustion, enhances fuel combustion efficiency, and reduces CO emissions. Higher oxygen levels promote more thorough oxidation reactions, ensuring a greater proportion of fuel conversion to carbon dioxide (CO₂) rather than carbon monoxide (CO). However, the influence of oxygen concentration on fuel combustion behavior during sintering is more complex. Internal fuel combustion in the sintering bed is simultaneously affected by heat transfer and oxygen concentration within the material layer. Increasing oxygen concentration leads to a lower fuel ignition point, extending the high-temperature zone and increasing oxygen consumption due to incomplete combustion. When the increase in oxygen concentration is small, the proportion of incomplete fuel combustion increases. This is because the additional oxygen initially promotes faster ignition but does not sufficiently support complete combustion throughout the sintering bed layer. Consequently, when the oxygen concentration reaches 23%, the sintering combustion efficiency decreases to 94.4%, the sintering temperature drops, and the CO concentration in the combustion products increases. This phenomenon highlights the delicate balance between oxygen availability and combustion dynamics during sintering; insufficient oxygen results in incomplete combustion and increased CO emissions. Further oxygen concentration increases, combined with rising layer temperature, optimize the kinetic conditions for CO secondary combustion. This indicates that excess oxygen supports initial combustion and facilitates further CO oxidation to CO₂ in the high-temperature regions of the sintering bed. Consequently, the sintering combustion efficiency improves, and the CO emission concentration decreases. When the oxygen concentration is increased to above 27%, the combustion efficiency exceeds 94.9%, significantly optimizing fuel utilization efficiency during sintering and reducing CO emission concentration in the sintering flue gas. This indicates a threshold oxygen concentration beyond which the benefits of enhanced combustion efficiency and reduced emissions become pronounced. These findings highlight the importance of carefully controlling oxygen levels during sintering to achieve both energy efficiency and environmental goals. This study provides valuable insights into how oxygen concentration improves combustion efficiency and reduces emissions during sintering, contributing to energy efficiency and environmental protection in industrial applications.