Abstract: Ilmenite is mainly utilized as a resource through reduction smelting processes, and the presence of impurity elements, especially magnesium, has a great influence on the reduction of ilmenite. The influence mechanism of magnesium element in the reduction process of ilmenite is analyzed at the crystal structure level. The results show that the bond length of the Mg-O bond is smaller than that of the Fe-O bond, so the crystal structure of MgTiO₃ is more compact and difficult to reduce. The doping of Mg²⁺ will replace the Fe²⁺ in the FeTiO₃ lattice, resulting in the crystal structure of FeTiO₃ in ilmenite becoming dense and the reducibility becoming worse. During the reduction process, Mg²⁺ will dissolve Ti⁴⁺ and Fe²⁺, which share O^2-, to form a solid solution that is difficult to reduce, resulting in poor reducibility. Therefore, the influence of magnesium works through the whole process of ilmenite reduction smelting.