Abstract: In order to determine the optimal inflation pressure of air cannon in the course of clearing coal bunker blocking, we established a mathematical model of the air cannon busting and determined the appropriate boundary conditions and initial conditions for different operating conditions；we used the Fluent software to simulate the working status under 0.4 MPa to 0.8 MPa inflation pressure of the air cannon bursting, and got the pressure cloud diagrams and velocity cloud diagrams of different times after the air cannon opened．The results showed that within the pressure range of the system, the higher the initial pressure, the more obvious of the effect of clearing the coal bunker blocking．When the working pressure reached 0.8 MPa, the clearing effect is the best