<p>The electrolysis–persulfate oxidation technology (EC-PS) was applied for the synergistic and harmless treatment of cyanide tailings. This study focused on investigating the influencing parameters of the oxidation process on cyanide removal efficiency and further exploring the mechanism of cyanide removal. The results indicated that the cyanide removal efficiency was 82.14% under optimal conditions of liquid–solid ratio of 5:1, persulfate concentration of 20&#xa0;g·L⁻¹, current density of 105&#xa0;mA·cm⁻², plate spacing of 3&#xa0;cm, initial pH of 7, and treatment time of 3&#xa0;h. Leaching toxicity analysis showed a cyanide content of 0.52&#xa0;mg·L⁻¹ in the tailings post-treatment, which met the general industrial solid waste standard. Cyanide removal predominantly occurred through indirect oxidation involving SO₄⁻, O₂⁻, and HO·, alongside the direct oxidation of S₂O₈²⁻. Contributions to oxidation were as follows: SO₄⁻ (49.03%), O₂⁻ (23.67%), and HO· (7.80%). The electric field facilitated the directional migration of S₂O₈²⁻ and metal cyanide complex ions toward the anode, enhancing electron transfer at active sites and promoting the destruction of O–O bonds in S₂O₈²⁻, leading to the formation of active free radicals such as SO₄⁻ and O₂⁻, which effectively oxidized and decomposed cyanide and pyrite. Furthermore, the oxidation of pyrite released Fe²⁺, which could also function as an activator to enhance the conversion process of S₂O₈²⁻ into SO₄⁻. However, the generated Fe³⁺ had a reverse effect on the oxidation of pyrite. Ultimately, the process broke S–S bonds and accomplished the cyclic conversion between Fe³⁺ and Fe²⁺.</p> Graphical Abstract <p></p>