The gas circulation sintering process has the effect of energy saving and emission reduction, and meets the requirements of green, low-carbon transformation and high-quality development. Due to many influencing factors, some gas circulation sintering production processes still have the actual problem of reduced sinter output. At the same time, the CO emission in the gas deserves attention. The coexistence of multiple factors such as oxygen content, temperature, moisture content of circulating gas and the influence of single factor change on sintering indicators and average CO concentration are researched, suitable process parameters are obtained, and effective measures are proposed to optimize the gas circulating sintering process. The results show that: under the condition of high temperature and moisture content of circulating gas, the whole process of oxygen enrichment or mid-front step oxygen enrichment (21%-23%) of the circulating gas is beneficial to improve the sinter production capacity and inhibit the generation of CO. The appropriate O₂ volume fraction should not be less than 20%, while the appropriate gas temperature should not be higher than 180-200 °C, and the moisture volume fraction should be less than 5%; When the O₂ volume fraction increases from 17% to 21%, the average CO concentration can be reduced by 10%; For the second sintering gas circulation process in the Baoshan base, two optimization measures are proposed: circulation mode optimization and gas temperature optimization. The circulating flue gas O₂ volume fraction, flue gas temperature and moisture content are accurately controlled to about 20%, 160 °C and 1%, respectively, so as to increase the sinter production capacity and break through the technical bottleneck of gas circulation sintering technology.