Abstract: Aiming at the problem of serious air leakage from working face to goaf,a new method to measure and calcu- late air leakage quantity is put forward. Analyzing the air balance principle of air leakage of goaf,the type curve of air leakage distribution can be obtained by measuring the air speed distribution in working face. As measuring the section- al area of working face is difficult,the error of calculating air leakage quantity directly is big. For that reason,the pro- jection area of regression curve of measured air speed is introduced,and then S-v(x) figure can be plotted. Under the circumstances of the foreign air quantity,such as goaf gas emission quantity,nitrogen-injection flux and air leakage quantity,is known,the ratio of foreign air quantity and the increment between the air speed projection area of air leak- age side and return air side caused by foreign air quantity,namely the air leakage weight d on unit air speed projection area is obtained. According to air leakage quantity d,the exchanged air quantity caused by air leakage between work- ing face and goaf cab be calculated. Combine the measured air speed of working face E1S6 in Jiudaoling Mine,after calculation we can obtained that,the weight of air leakage quantity area is 0. 087 33 m when the nitrogen-injection flux is 25 m33 / min,and then we can obtained the air leakage quantity of working face is 65. 5 m3 / min,return air3 leakage is 90. 6 m / min,which accounts for 10-15 percent of the total air quantity of the working face,namely 650 m / min. The results accord with the general empirical range.