Abstract: B 4C particles reinforced MoSi 2 based composites were prepared by rapidly heat compression molding. The influence of particle content on the microstructure, mechanical properties and tribological behavior of MoSi 2 based composites was investigated. The results show that with the increase of B 4C particle content, the hardness of the composites is increased, while the friction coefficient and wear rate decreased. It is supposed that B 4C retarded the oxidation of MoSi 2, prevented the formation of glass phase between crystals, and improved the interface combination of crystals. The tribochemical product is also beneficial for the modification of the tribological properties of MoSi 2 composites.