Abstract: Air leakage control in goaf of U+L working face has always been one of the important topics of mine fire prevention and control. In order to study this problem, adiabatic oxidation temperature rise test, field monitoring and numerical simulation were adopted. Based on the determination of characteristic parameters of coal spontaneous combustion limit, the distribution law of "three zones" in goaf was studied by taking an actual mine in Shaanxi Province as an example, and further revealed. Characteristics and danger of spontaneous combustion in goaf. It is found that the lower limit oxygen concentration of spontaneous combustion of coal in the goaf is 12.9%. U+L ventilation mode has a serious impact on the division of "three zones" in the goaf. The fluctuation of "three zones" in the goaf on the intake side will occur due to the influence of air leakage in the auxiliary haulage roadway. The numerical simulation can more intuitively reflect the distribution characteristics of the dangerous zones. The research results have certain guidance and reference significance for mine fire prevention in the same kind of working face.