At present, the Kroll method is still the only industrialized method for the production of metal titanium, and the newly developed electrolysis method and metal thermal reduction method are both in the research stage. In this paper, the reduction mechanism of the primary reduction stage and the law of the amount of magnesium are studied for the titanium powder prepared by the multi-stage reduction process. Through analysis and result verification, increasing the amount of magnesium can promote the kinetics of the reaction, which is conducive to the improvement of the reduction of TiO₂ and inhibits the residual magnesium impurities. Magnesium is mostly wrapped in fluid form on the surface of titanium dioxide particles for mass transfer formation during the primary reduction process Multiphase microspheres and titanium oxide are sintered under high temperature to form the product morphology of the pore network structure. On the basis of considering the utilization of magnesium and the quality of the actual deep reduction product, the stoichiometric ratio is determined by experiments as the best ingredient ratio. The oxygen content of the primary reduction product of this ratio can reach 16.04wt.%, the specific surface area and the median particle size are 1.76m^₂/g and 34.39μm, respectively, and the O and Mg content of the prepared titanium powder are 0.274wt.% and 0.010wt.%, respectively.