This work reported the microstructural evolution and grain growth kinetics of ZrB2-SiC composites containing 10, 20, and 30 vol% SiC during heat treatment at 2000 degrees C. The coarsening of ZrB2 occurred in the three systems, whereas the obvious coarsening for SiC appeared only in the composite with 30 vol% SiC. The kinetics analysis showed the ZrB2 grain growth rate in the ZrB2-30 vol% SiC was 25 times lower than that for ZrB2-10 vol% SiC during heat treatment. Furthermore, the grain growth controlling mechanisms of ZrB2 and SiC were discussed. In addition, it was found that the heat treatment had little effect on Vickers hardness and fracture toughness of ZrB2-SiC.