Abstract: For the spoil dump of open-pit coal mines，in the context of the increasing discharge vol⁃ ume and the constraint of land area，taking the spoil dump of the Baorixile open-pit coal mine in Inner Mongolia as the object，based on the Geostudio software platform，combined with the limit equilibrium method and numerical simulation method，a systematic study is conducted on the influence laws of slope gradient，slope height，and rock and soil mechanical properties on stability. By constructing a 2D homoge⁃ neous model，the Morgenstern-Price method is used to compare and analyze the safety factor under differ⁃ ent slope gradients (15°~35°) and slope heights（25~50 m），and the mechanical parameter sensitivity of 4 types of rock and soil（sandy mudstone，mudstone，fine sandstone，and medium-coarse sandstone）is dis⁃ cussed. The results show that the safety factor decreases linearly with the increase of slope gradient and slope height. When the slope height increases from 25 m to 50 m，the safety factor decreases by 30.6%; when the slope gradient increases from 15° to 35°，the decrease is 32.8%. Cohesion is the most sensitive parameter affecting stability，and the internal friction angle needs to act in synergy with cohesion. The study further proposes that by optimizing the rock and soil ratio，that is，prioritizing the use of high-cohe⁃ sion materials such as mudstone and sandy mudstone，it is possible to achieve the balance between loading capacity and safety under the limited land area，providing a theoretical basis for the design of open-pit coal mine spoil dumps and slope stability.

Key words: dump slope, Morgenstern-Price method, mechanical properties, limit equilibrium meth? od, numerical simulation