The air leakage of the sintering machine seriously affects the economic and technical indicators during the sintering production process, which will lead to the reduction of the effective air volume through the bed of material, the deterioration of the sintering minerals and quality indicators, and the increase of the fan power consumption. In order to monitor the air leakage of the sintering machine in real time and provide timely guidance for the air leakage control, an online monitoring system for sintering air leakage is designed based on the oxygen balance method. The oxygen content of different sintering fume monitoring points is collected through the zirconia oxygen meter, and a calculation model of the air leakage rate is built based on the Visual Studio platform, which realizes the real-time monitoring of the air leakage rate and abnormal alarm in different sections of the sintering system. By analyzing the key factors and parts of air leakage of the sintering machine, combined with timely leak plugging and system maintenance, the air leakage rate of the whole sintering system is decreased from 40.72% to 34.15%, a decrease of 6.57%, reaching the domestic advanced level and promoting the low-carbon and green development of sintering.