Abstract: In order to study the failure mode of double weak layer slope of burnt rock in opencast coal mine, the failure and deformation characteristics of the slope were analyzed by means of FLAC3D numerical simulation, and the mechanical model of the slope was established, considering the influence of burnt rock mass and groundwater on slope stability and the control of weak interlayer on slope, the failure mode of slope sliding under different mechanical conditions is deduced based on the limit equilibrium method. The simulation results show that the upper rock mass and the back edge of the burnt rock mass have larger displacement in the horizontal direction, faster deformation speed, obvious plastic deformation; plastic zone exists along the lower weak layer, and the deformation speed of the rock mass in the control area increases. The results of mechanical analysis show that when the stability of slope is controlled by the upper weak layer, the upper rock mass moves and deforms along the upper weak layer; when the slope is controlled by the lower weak layer, the rock mass slips along the lower weak layer, the back edge is split, and the slope is sheared along the lower weak layer; when the vertical height of the trailing edge crack plane reaches the distance between two weak layers, the crack plane lies below the upper weak layer, and the slope stability is controlled by two weak layers at the same time. If the upper rock mass is cracked, the cracked rock mass moves along with the deformation of the lower rock mass; if the upper rock mass remains stable, the lower rock mass slips away from the upper rock mass; and if the upper rock mass loses stability as a whole, the upper rock mass is fractured by the tensile fracture of the burnt rock mass at the back edge of the upper rock mass, the lower part of the rock mass along the lower weak shear instability, the upper rock mass as a whole with the lower rock mass deformation. Taking the southern end of the second mine of Dananhu as an engineering example, substituting mechanical parameters, the safety factor of upper rock mass is 0.942, and the safety factor of lower rock mass is 1.070, and the rock mass is in critical slip state, the slope is subject to a staged sliding-tension instability controlled by the upper and lower weak layers.