The direct reduction–magnetic separation process based on coal is considered to be one of the most important methods that can effectively utilize high-phosphorus oolitic hematite. In this study, the mechanism of the effects of CaCO₃ and Na₂CO₃ on the dephosphorization of high-phosphorus oolitic hematite during the direct reduction process was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results showed that Na2CO3 and CaCO3 reacted with Al₂O₃ and SiO₂ during the direct reduction process, inhibited the generation of hercunite (FeAl₂O₄) and fayalite (Fe₂SiO₄), and promoted the reduction of metallic iron (Fe). Furthermore, the reaction inhibited the reduction of apatite and prevented the generation of FeP₂. Na₂CO₃ could change the form of phosphorus in the gangue from Ca₃(PO₄)₂ to Na₂Ca₄(PO₄)₂SiO₄. Increasing the dosages of Na2CO3 and CaCO3 in the dephosphorization agent and increasing the content of Na₂CO₃ in the dephosphorization agent were beneficial to the growth of metallic iron particles, and increasing the dosage of Na₂CO₃, CaCO₃ in the dephosphorization agent had more significant effects on metallic iron particles than increasing the content of Na₂CO₃ in the dephosphorization agent. The research conducted in this study is expected to provide a basis for the effective exploitation of complex and refractory iron ores.