The degradation efficiency and mechanism of ferrite (Fe(VI))/calcium oxide (CaO₂) combined treatment on dimethyl phthalate (DMP) were studied. Multi-factor experiments were carried out based on the Box-Behnken experimental design in Response Surface Method. Relationships between the removal rate of DMP and Fe(VI)dosage, CaO₂ dosage and reaction time were fitted by quadratic polynomial and stepwise regression method, and the experimental conditions were optimized. DMP could be effectively removed by Fe(VI)/CaO₂ under neutral pH conditions, and the degradation process conformed to the pseudo-second-order kinetic model. The maximum degradation rate of DMP predicted by the model reached 95.57% when the molar ratio of Fe(VI)/CaO₂/DMP was 1.1/4.4/1, which was close to 90.14% obtained by verification experiments, indicating that the model possessed a good simulation and predictive performance. HCO₃^- and Mg(Ⅱ) inhibited the degradation of DMP to a certain extent. The results of free radical scavenging experiments revealed that hydroxyl radical (HO·) and superoxide radical (O₂^-·) made significant contributions to the degradation of DMP, demonstrating that Fe(VI)and CaO₂ could form Fenton-like reagents to synergistically degrade pollutants. The main degradation pathways of DMP included hydrolysis of ester group, oxidation of side chain and hydroxylation of benzene rings. The main degradation products were monomethyl phthalate, 2,5-dihydroxybenzoic acid, isophthalic acid, oxalic acid, etc.