Abstract: Root damage is a critical ecological issue affecting vegetation in semi-arid underground coal mining areas. The mechanisms and influencing factors of root stress damage induced by stress changes in the root-soil layer due to mining-induced rock mass fracturing require further investigation. This study establishes a numerical model of root stress damage in the main root of plants based on FLAC^3D, incorporating the quasi-cohesion and anchoring theories. By controlling variables, the model simulates the macroscopic mechanical disturbance characteristics of the plant-soil composite unit and root system under different mining conditions, root-soil layer mechanical properties, and root density and diameter. State response functions of root stress to different mining depths, advance rates, coal seam depths, and coal seam thicknesses are then constructed. The results show that the roof stress generated by the fracturing of the mined bedrock is transmitted to the root-soil layer. The extent of plastic zone damage in the root-soil layer increases with the advancement of the working face. The maximum shear stress on the upper and lower parts of the disturbed zone roots increases, and the inconsistency of stress on the upper and lower parts of the root system is a major cause of root damage near the boundary of the goaf. Under single-variable control, the maximum shear stress on the disturbed zone roots increases with increasing coal seam thickness and decreases with increasing mining depth. However, the advance rate only affects the time it takes for the overlying rock stress to transmit to the root-soil layer, with little effect on the extent of plastic zone damage in the root-soil layer. With increasing internal friction angle and cohesion, the shear strength of the soil increases, reducing the area of shear failure in the root-soil layer and thus protecting the roots. As root diameter increases, the stress per unit area on the root decreases, while changes in root density have a relatively small impact on root stress and the extent of plastic zone damage in the root-soil layer. The response functions between the stress difference between the upper and lower parts of the root system and coal seam thickness, mining depth, and advance rate are all continuous and gradually changing functions, while the response function with respect to the advance distance is a step change function. Vegetation protection or source reduction requires controlling the mining subsidence state or employing backfilling, partial backfilling, and other static mining techniques to minimize the stress damage to plant roots caused by mining disturbances. The research findings enrich the understanding of plant damage mechanisms induced by underground coal mining in semi-arid areas.