Rare earth mine is the treasure of China's strategic resources, and ensuring its safe, environmentally friendly and efficient mining has become a key issue of long-term concern and urgent solution for all walks of life. A comprehensive evaluation model based on grey correlation theory (GRA) and fuzzy hierarchical analysis method (FAHP) is innovatively proposed to address the slope stability of ionic rare earth mines in the mining process. Through an in-depth analysis of an ionic rare earth mine in Gannan, five key factors affecting slope stability are identified, including slope geotechnical parameters, slope topographic and geomorphological conditions, leaching process, hydrometeorological characteristics and seismic effects, and further subdivided into nine fine-molecular factors. The fuzzy complementary judgement matrix constructed by FAHP is used to achieve the deep integration of qualitative and quantitative analysis. On this basis, GRA is used to optimise the weight calculation, which greatly improves the accuracy of determining the weights of each factor, and makes the weights of each factor in the evaluation system more in line with the actual situation. After rigorous verification of actual cases, this model shows good effectiveness and reliability in assessing the stability of slopes, and can accurately predict the evolution trend of the slope state, which provides a strong scientific support for preventing the risk of slope instability in advance. In summary, the FAHP-GRA comprehensive evaluation model not only greatly improves the scientific and accuracy of the slope stability evaluation of ionic rare earth mines, but also has far-reaching significance for the sustainable and stable development of China's rare earth resources as well as the healthy development of the related strategic industries, and also provides valuable reference examples for the slope stability research and practice of the similar mines in the future.