Abstract: A new technique named self-propagating high-temperature synthesis with a stage of metallurgy was proposed to prepare boron powder. The adiabatic temperature (Tad) in B2O3-Mg reaction system was calculated to be 2604 K, through which the thermodynamic data of correlative reactions were analyzed to determine the feasibility of the self-propagating high-temperature synthesis reaction consequently. The DTA results indicate that the apparent active energy of the exothermic peak of B2O3-Mg reaction system is 903.75 kJ·mol^-1 with reaction order equal to 1, and the XRD results show that the combustion products are composed mainly of MgO, Mg3B2O6 and B2O3. Thus the three-step leaching conditions were confirmed. The purity of boron powder can be up to 92.43% as indicated by spectral and chemical analyses. Its mean grain size is 0.5-0.8 μm.