Abstract: In order to obtain an air distribution volume of the coal mining face under U type ventilation modeaffected to the air leakage intensity of the goaf,a study was conducted with the numerical simulation and the site actual measurement combined metho.Based on No.1312 coal mining face in Zhangie Mine as a prototype, a nonlinear seepage 3D mathematical and physical model of the U type ventilation goaf was established.A sinmulation calcuation was conducted on the fow feld of the goaf under different air velocity of the air intake gateway.The site actual measured results were fited to thenumerical simulation resuts. With the application ofthe iregular area calculation software and the Origin numercal analysis software, the distrbuton functon of the air velocity area density in the goaf was obtained,and the calculation formula of the coresponding area in the arbitrary air velocit area of he goaf was deduced.Acording to the air leakage intensitythe spontaneous combustion zones of the goaf were divided.The study results showed that he area and with of the spontaneous combustion zone in the goaf would be increased in the Langmuir function with the airvelocity in the air intake gateway increased.According to the limit width of the spontaneous combustion zone in the goaf.a mininum forward speed of the coal mining face was obtained.The actual forward speed of the coal mining face was higher than the obtained minimum forward speed of the coal mining face could be one of the important conditions to judge no spontaneous combustion occurred in the goaf.