Transition metal Fe2+ is the most economical, effective and environmentally friendly PS activation substance, but Fe2+ is prone to be oxidized and loses its activation ability, resulting in poor continuous effect of the Fe2+/PS system. In order to improve the efficiency of the Fe2+/PS system in oxidizing and degrading organic pollutants, iohexol, a commonly used iodinated X–ray contrast media in medical field, was taken as the target pollutant，and its degradation in four advanced oxidation proeesses such as UV/PS，Fe(C2O4)3 3–/PS，UV/Fe(C2O4)3 3–/PS and Fe2+/PS was studid. The effects of Fe(C2O4)3 3– concentration, ultraviolet light intensity and pH on the degradation of iohexol and PS decomposition in UV/Fe(C2O4)3 3–/PS system were examined, and then the Fe2+ concentration change and its conversion rate in the system were analyzed. The results verified that the oxidation decomposition rates of iohexol in the four advanced oxidation systems were 83.8%, 7.0%, 98.8%, and 69.9% respectively, among which the UV/Fe(C2O4)3 3–/PS system could promote the reduction of ferrous irons through ultraviolet light, Fe2+ that activates PS in the solution was gradually released, and the degradation of iohexol was the most efficient and complete. As the concentration of Fe(C2O4)3 3– increased, the decomposition rate of PS in the UV/Fe(C2O4)3 3–/PS system increased, while the degradation rate of iohexol first increases and then decreases. Under four different initial Fe(C2O4)3 3– concentrations (20, 50, 100, 200 μmol/L), the degradation rate of iohexol is in the order of 100>200>50>20 μmol/L. In the UV/Fe(C2O4)3 3–/PS system, the Fe2+ concentration first increases rapidly and then slowly decreases, the degradation rate of iohexol, the decomposition rate of PS and the highest conversion rate of Fe2+ are all positively correlated with ultraviolet light intensity and negatively correlated with pH. Therefore, the use of ultraviolet light to reduce iron ions can greatly improve the Fe2+ activation efficiency, and the system has strong adaptability to influencing factors such as light intensity and pH, and has great application prospects in the field of advanced oxidation in water treatment.