Abstract: The Huangyukou slope in Yanqing is rich in dolomite resources. Under the combined action of excavation, rainfall and artificial mining, there is a serious instability phenomenon. There are many cracks on the front edge of the landslide and the surface of the landslide. At present, the instability mechanism and support countermeasures of the slope are lack of detailed analysis. In this paper, the instability mechanism of strongly weathered dolomite slope is studied by means of field investigation and numerical simulation experiment, and the supporting effect of NPR anchor cable on this kind of broken rock slope is verified by field monitoring. The results show that the cracks in the dolomite slope are mostly tensile and shear cracks, and the landslide mainly occurs creep deformation. The landslide belongs to the traction bedding rock landslide. The influence of rainfall on the slope is mainly the result of the combined action of saturated pore pressure and unsaturated pore pressure of rock and soil. Excessive rainfall will lead to the softening of bedrock at the leading edge of the slope, resulting in the occurrence of landslide. Through the excavation method to enhance the stability of the slope, the stability of the slope in the mining area is obviously improved after the reinforcement of the NPR anchor cable, and the Newton force is basically maintained above 300 kN, which can realize the stability control and remote real-time monitoring and early warning of the slope.