Hot air sintering coupled with gas injection technology is a new type of enhanced sintering technology for hot air circulation sintering and gas injection in the hot air hood, which can improve the quality of sintered minerals, reduce the consumption of burning solid fuel and pollutant emissions. When the uniformity of the flow field is low, the ejected gas is easy to enrich, catch fire and escape, which seriously affects the operation safety. Therefore, Fluent software is used to simulate the flow field in the hot air hood of a 500 m² sintering machine in a sintering plant, and the results show that: After the hot air enters the hot air hood, it is biased to one side of the material surface, and a return dead zone is generated under the air intake, so that the outside air enters the hot air hood and obstructs the ejected gas from entering the material surface, resulting in gas enrichment near the nozzle pipe. By optimizing the structure in the hot air hood, the maximum air speed entering the material surface is reduced from 6.42 m/s to 2.72 m/s, the variance of the air speed of the material surface is reduced from 2.70 to 0.25, and the maximum gas mass fraction of the nozzle outlet area and the material surface are reduced from 1.82% and 0.98% to 1.30% and 0.53%, respectively, which are reduced by 57.63%, 90.74%, 28.57% and 45.92% compared with the original structure. After optimizing the side sealing structure, the average air speed of the side air leakage is reduced from 1.17 m/s to 0.22 m/s, which is 81.2% lower than the original structure, ensuring the safe, efficient and stable operation of the gas injection coupled with hot air circulation sintering system.