Abstract: Abandoned high-sulfur coal mines will become deeply buried acid-producing contamination sites, posing hazards to adjacent aquifers and surrounding environments. Furthermore, mining effects and the complex spatial distribution of abandoned mines complicate the assessment of the contamination processes and degrees in adjacent aquifers. Focusing on a certain abandoned coal mine, this study examined the migration characteristics of SO₄ ²⁻ pollution in acid mine drainage using numerical simulations by taking sulfate (SO₄ ²⁻) as the characteristic contaminant and considering the impact of the fractures formed by multi-seam mining on the aquifer structure. Furthermore, it analyzed the influence of the fluid diffusion coefficient on the transport of contaminants in the aquifers. The results show that the horizontal migration area of SO₄ ²⁻ in the sandstone aquifers of the Tongziyan Formation increased over time, but the rate of increase gradually decreased. Concurrently, the vertical permeability coefficient of the sandstone aquifers increased by 10 times, indicating elevated spatial variability. The simulation results show that 5, 10, and 15 years after the coal mine was abandoned, the maximum horizontal migration distances were 215 m, 414 m, and 612 m, and the maximum vertical migration distances were 50 m, 65 m, and 70 m, respectively. The SO₄ ²⁻ migration distance and contamination range increased with the diffusion coefficient and the acid-producing time. Compared to the horizontal direction, the variations in the SO₄ ²⁻ concentration were more sensitive to the diffusion coefficient in the vertical direction. Based on the simulation results, as well as the actual conditions of the abandoned coal mine, this study proposed the comprehensive prevention, control, and management strategy of “reducing mine recharge, blocking contamination process, and treating contamination at the end”. The results of this study will provide a theoretical basis for the treatment, prevention, and control of contamination caused by acid mine drainage in the abandoned coal mine and offer a scientific reference for other similar mines.