Abstract: In order to study the activation laws of mining fault in the edge coal face, based on the mining of the residual edge coal in No.3 normal fault in Xinlongzhuang Coal Mine 5313 working face, the evolution laws of fault stress and fault slip in different strata are studied by numerical simulation and the possibility of fault activation instability induced by mining is analyzed. The results show that with the decreasing of the distance between the face and the fault, the shear stress and normal stress of the fault plane increase, their ratio increases, and the slip of the fault also increases, and the possibility of fault activation instability increases. When the distance from the face to the fault is less than 30 m, the activity of fault is the most obvious.