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Zero-valent iron/peroxymonosulfate (Fe⁰/PMS) has been considered as a promising approach for wastewater treatment. Anions and cations are widely present in wastewater and have significant effects on the performance of the Fe⁰/PMS system for wastewater treatment. Thus, in the present study, tartrazine was selected as the target model; SO₄²⁻, NO₃⁻, HCO₃⁻, and Cl⁻ were selected as representative anions and Ca²⁺, Cu²⁺, Mg²⁺, and Mn²⁺ were chosen as representative cations. The effect of these anions and cations on tartrazine removal and major radicals in the Fe⁰/PMS were systematically investigated. The presence of a certain concentration of SO₄²⁻ and Cl⁻ had positive, NO₃⁻ had negative, and HCO₃⁻ had negligible effects on tartrazine removal in the Fe⁰/PMS system. SO₄²⁻ and HCO₃⁻ had a small effect on the contribution proportion of reduction, SO₄^•− and ^•OH; a certain concentration of Cl⁻ could enhance the contribution proportion of ^•OH; and NO₃⁻ would decrease the contribution proportion of SO₄^•− and ^•OH. A certain concentration of each of Ca²⁺, Cu²⁺, Mg²⁺, and Mn²⁺ could enhance the tartrazine removal in the Fe⁰/PMS system. Ca²⁺, Cu²⁺, and Mg²⁺ had no effect of the contribution of reduction, SO₄^•− and ^•OH, while a certain concentration of Mn²⁺ could enhance the contribution proportion of SO₄^•−. These results can provide some references for the Fe⁰/PMS system to treat actual wastewater containing anions and cations.