Abstract: It was suggested that B4C micropowder would be produced by self-propagating high-temperature synthesis (SHS), with taking B4O and C raw materials and Mg powder as reducing agent, which has many advantages such as simple process, high purity and fine granularity of product. The adiabatic temperature of the B2O3-Mg-C reaction system was calculated in order to verify the feasibility of the SHS reaction. The results of X-ray diffraction analysis of the products show that B4C will be gained through SHS and there is little C in the product. It is found that the B4C grain is very fine by SEM, and it is observed that in B4C powder the single crystal is fully growing together with incompletely growing polycrystal by electronic diffraction patterns. Purity of B4C is shown not lower than 98% by spectrum analysis, while it is slightly lower by chemical analysis. Special attention is paid to the reaction mechanism of SHS.