Abstract: Open-pit mine dump is shelter of waste soil and rock. The stability of dump is directly related to the safety of mining production and personnel life and property, and is a key focus of mining safety management. In order to study the stability of high slope of Nandagou Dump and ensure the safety of dump slope in the later stage, an in-depth analysis of the engineering geological data of the dump site is conducted, and a numerical calculation model for a typical slope profile is established based on on-site investigation and stacking status maps. The innovative use of FLAC^2D numerical software combined with quantitative evaluation and displacement deformation monitoring is employed to comprehensively analyze the stability of the Nandagou dump slope, reproducing the evolution process of potential slope failure. By analyzing the stability calculation results and displacement monitoring data, the results show that the failure mode of its slope is the top platform tearing, and the lower part is cut out in a circular arc shape; and after qualitative evaluation and quantitative calculation, the stability coefficient of the slope under three working conditions is higher than the safety coefficient specified in the specifications, meeting the requirement of safety level one, so the dump slope is generally in a stable state; and the cumulative deformation of dump has been maintained within the warning range for over a year, indicating strong self stabilization ability. The comprehensive analysis and evaluation method combining numerical simulation and deformation monitoring is accurate and reasonable, which provides safety guarantees for mining and waste rock dumping, as well as technical guidance for stability analysis of the dump.