Abstract: The waste dump is a key site for open-pit mines to dispose of overburden generated during mining operations, and its long-term safety and stability constitute the core task of mine safety management. The slope stability of the waste dump is comprehensively affected by multiple factors such as the physical properties of dumped materials and the sequence structure of dumping layers. To improve the slope stability of the waste dump and maximize the slope angle to increase its effective capacity, a model for the dumping sequence structure of waste dump slopes was established. By comprehensively applying the finite element method, limit equilibrium method and similar simulation test, this study systematically analyzed the influence laws of main dumped materials on slope sliding modes and stability under different sequence structures, and mainly investigated the influence mechanism of water content changes on the mechanical properties of dumped materials. On this basis, the study further explored the enhancement effect of the optimal dumping sequence structure on slope stability under the condition of dynamic changes in material properties, and optimized the sequence combination, aiming to determine the dumping sequence combination mode of the waste dump with the best slope stability and the most reasonable engineering conditions. The results show that under the natural water content state of rock and soil, the internal friction angles and cohesions of fine sandstone, coarse sandstone and mudstone are 21.6° & 31.27 kPa, 17.3° & 19.57 kPa, and 20.7° & 37.09 kPa, respectively. With the increase of water content gradient, the internal friction angles and cohesions of all groups of dumped materials decrease to 16.2° & 22.97 kPa (fine sandstone), 13.2° & 14.73 kPa (coarse sandstone), and 12.2° & 21.53 kPa (mudstone). Comparative analysis reveals that the mechanical parameters of mudstone are the most sensitive to water content changes. Through analyzing the influence laws of dumped material parameters and sequence structure changes on slope stability, the optimal dumping sequence structure is finally determined as loess-mudstone-coarse sandstone-fine sandstone.