Abstract: Due to the presence of transition metal elements such as Fe and Mn in copper tailings, these substances exhibit significant catalytic oxidation performance in the liquid phase. Meanwhile, the abundant alkaline oxides such as Ca and Mg in it have good adsorption properties for SO2 and NO_x, which gives it a natural advantage as a desulfurization and denitrification absorbent. In addition, the utilization of copper tailings for flue gas treatment also has the advantages of wide raw material sources, low cost, and the simultaneous recovery of metal ions, which conforms to the environmental protection concept of "waste treatment with waste". This study proposes the use of copper tailings slurry to simultaneously remove SO₂ and NO_x from flue gas. Firstly, the desulfurization and denitrification performance and related mechanisms were investigated through basic experiments, and the strengthening effect of thermal activation treatment on the activity of tailings was explored. The results of basic performance and thermal activation studies show that the copper tailings slurry has an extremely significant effect on the removal of sulfur dioxide, maintaining a 100% removal efficiency throughout the test period. However, the material's ability to treat nitrogen oxides is relatively weak. Even after optimizing key parameters such as the solid-liquid ratio, reaction temperature, gas flow rate, and oxygen content, the highest removal rate is still only 45%. To address this technical bottleneck, this study modified the copper tailings by thermal activation. Through systematic experiments, the optimal process conditions of 800°C activation temperature and 120 minutes activation time were determined. After activation under these conditions, some of the carbonates in the copper tailings decomposed into oxides, increasing the specific surface area and active sites, and the denitrification efficiency increased to 51%, confirming that thermal activation has a significant strengthening effect on denitrification performance. Although thermal activation improved the denitrification efficiency, a 51% removal rate is still difficult to meet the actual engineering requirements. Therefore, oxidants were further introduced to significantly enhance the removal effect of NO_x through oxidation synergy. Experimental results show that in the denitrification process of copper tailings, potassium permanganate and sodium chlorite exhibit more significant synergistic effects compared to other oxidants such as hydrogen peroxide and sodium hypochlorite. Among them, the experimental results show that when the concentration of potassium permanganate is 38 mmol/L, the system's denitrification efficiency is the highest, reaching 94.5%; while sodium chlorite, at an addition amount of 50.6 mmol/L, has a denitrification efficiency of 83.9%. Both oxidants can effectively oxidize the insoluble NO to the easily absorbable NO₂ or further convert it to nitrate, thereby significantly improving the denitrification efficiency. Further, when sodium chlorite and potassium permanganate are used in combination, it was found that they have a synergistic denitrification effect. When the ratio of the oxidants is adjusted to 51 mmol/L and 25 mmol/L, the system's denitrification efficiency reaches the optimum, significantly outperforming the treatment effect under the condition of a single oxidant. In conclusion, after thermal activation and the synergistic enhancement of oxidants, copper tailings can not only maintain high-efficiency desulfurization but also significantly improve denitrification capacity, demonstrating good industrial application potential.