Abstract: Coal mining under faults is prone to bring a series of problems, such as coal mine overburden damage and surface subsidence. The predecessors have limited understanding of the stress change and mining activation law caused by the change of reverse fault dip angle under thick loose beds. This paper systematically studies the characteristics of stress changes and fault slip on each fault zone when the footwall coal seams of reverse faults with different dip angles are gradually mined, taking F1 reverse fault of Kouzidong Mine in Huainan Coalfield as an example, building a three-dimensional numerical model, based on FLAC^3D numerical simulation software. The results show that the peak value of surface horizontal deformation on the side with fault is smaller than that on the side without fault, and the surface slope is more gentle. The slip deformation of the fault is related to the ratio of tangential stress and normal stress on the fault zone. The smaller the fault dip is, the more likely the fault is to slip. The larger the fault dip is, the weaker the slip phenomenon of the fault is. The upper part of the fault is easier to activate slip than the lower part of the fault. The process of fault activation can be divided into three stages: initial equilibrium period, shear slip period and activation failure period. The research can provide an important basis for the safety mining and prevention of coal mine under the influence of reverse fault in the area covered by thick loose layer.