It has been an important part of coal mine fire prevention to choose a reasonable ventilation and reduce air leakage. Shanxi Shigang Mine was taken as engineering background， With the method of numerical simulation， leakage air volume of three different ventilation modes with the change of air supply volume was simulated. The results showed that under the same kind of ventilation， the greater of the air supply volume， the greater the amount of air leakage; U+I-type ventilation can control the gas of the seam and the adjacent layer and have less impact on the amount of air leakage and it can solve the gas overrunning problem of coal face， upper corner and return air face achieve high yield and efficiency of mine safety.