Abstract: ZrB₂-SiC composite powders were synthesized by the boro/carbothermal reduction method using ZrO₂, SiO₂, B₂O₃ and activated carbon as raw materials. The thermodynamic analysis was conducted on the formation process. The effects of synthesis temperature and activated carbon content on the phase composition and micromorphology of ZrB₂-SiC composite powders were investigated. The results show that ZrB₂-SiC composite powder can be synthesized at temperatures of 1 400-1 450℃. Increasing the reaction temperature was beneficial to the synthesis of ZrB₂-SiC composite powder and the relatively pure ZrB₂-SiC composite powder was obtained by the reaction at 1 450℃ for 3 h. Meanwhile, the phase composition of the obtained ZrB₂-SiC composite powders was basically similiar with the activated carbon of excessive mole fraction of 50% and 75%.