Air leakage of sintering machine is an important technical index related to sintering energy consumption, output, cost, etc. To measure the air leakage rate of the sintering machine more accurately, based on wind speed method of new material surface, the fluctuation of the air volume of the material surface is considered, the arithmetic mean method is replaced by the curve integral method, the influence of ΔT on the calculated value of the effective air volume is reduced to make the calculated value of effective air volume is closer to the actual value, and a test is made in a 380 m² sintering machine. The result shows that the calculation method of calculating effective air volume of material surface and air leakage rate of sintering machine is accurate and reliable, which can help field staff grasp the air leakage of the system and provide guidance for production.