Abstract: In order to find out the influence of external conditions on the air leakage laws of the coal pile, in this paper, the theory of “three zones” of spontaneous combustion is used to analyze the air leakage laws of the coal pile and to deduce the air leakage equation of the coal pile. The formula shows that the particle size in the action term of the inertial force is proportional to the wind velocity of the air leakage. The wind velocity in the viscous force is proportional to the particle size, the relationship between the pressure gradient and the wind velocity is a quadratic equation. The air leakage law of coal pile was tested by taking into account such factors as particle size, pipe diameter, coal type and pile height. It is concluded that the particle size has a significant influence on the air leakage of coal pile; as the particle size decreases, the wind velocity of air leakage shows a downward trend and the decrease range varies from large to small; as the pipe diameter increases, the air leakage velocity increases, and the pipe diameter increases, the pressure drop is obvious; the wind velocity decreases exponentially with the increase of coal column height.