Abstract: The composite goaf formed after the close and very close distance coal seam mining has the characteristics of complicated structure and the special gas flow field. Therefore, it is difficult to determine the risk area of spontaneous combustion. Taking Wulan Coal Mine II020803 working face as a test face, first of all, we use UDEC numerical simulation software to simulate the overlying strata movement and the crack development, analyze the distribution of residual coal. Through the arrangement of three groups of longitudinal monitoring drillings in the central of compound goaf and two sides of roadway, and each drilling placed three measuring points, we monitor the change of O₂ concentration with the advancing of working face in composite goaf to determine spontaneous combustion "three zone" range and the scope of spontaneous combustion dangerous area.