Abstract: Acid mine drainage (AMD) generated in the process of coal gangue storage poses a serious pollution risk to the surrounding water environment. Based on the concept of "waste to waste", fly ash from coal combustion was selected for the study of contaminant removal in AMD. In response to the poor treatment effect of fly ash (raw ash), we compared the removal effect of fly ash under different modification conditions on the pollutants in AMD, screened out the fly ash-modified materials with the best removal effect, and analyzed the mechanism of the fly ash-modified materials in the process of pollutant removal at the microscopic level. The results showed that the Fe and Mn contents in the simulated AMD wastewater were reduced from 100 mg/L to less than 1 mg/L with 99% pollutant removal after treatment by Ca(OH)₂ flux roasting modified fly ash. The adsorption of Fe and Mn by Ca(OH)₂ flux-roasted modified fly ash was mainly monolayer chemisorption, and the adsorption was close to the equilibrium in 0-2 h. In addition, Ca(OH)₂ flux roasting modification increased fly ash surface roughness and pore number, and formed a hexahedral crystalline phase structure on the surface. Meanwhile, Ca(OH)₂ flux roasting activated Si and Al elements on the surface of the fly ash particles, increased their Zeta potential, reduced the free hydroxyl groups, and increased the fixed hydroxyl groups, which enhanced their adsorption capacity. The Ca(OH)₂ flux roasting modification significantly improved the removal efficiency of pollutants in AMD by fly ash, which provided a material and methodological basis for treating AMD by fly ash.