Ring cooler is a kind of important equipment that affects the thermal effect of the ring cooler process. The air volume of the ring cooler is an important parameter in the calculation of the latent heat recovery of the flue gas, while the accurate measurement of the air leakage rate is a difficult task. In this paper, by analyzing the material and energy flow balance relationship in the ring cooler process and establishing the calculation model of air leakage rate of the ring cooler, the air leakage rate of the ring cooler can be quickly calculated by obtaining real-time data through simple thermal measurements, and then combining the flue gas distribution function fitted with the flue gas temperature data, the leakage rate of the ring cooler can be calculated quickly, the air leakage rate calculation program can be developed, and the offline automatic calculation can be realized. The accuracy of the calculation model is verified by comparing the results of the air leakage rate of a 600 m² ring cooler in a steel mill with the results of field tests. The results provide a simple and practical estimation method for the air leakage rate measurement of the ring cooler, which is of great application value.