SiC whisker was produced through the reaction between carbon and silicon powders during the sintering of Al2O3-ZrO2-C materials. The thermodynamic conditions and growth mechanism were discussed. The results showed that rod-shaped and dumbbell-shaped SiC whiskers are formed, respectively. The main composition of the beads in dumbbell-shaped whisker is SiOX with a small amount of Na and Ca, but the rods are SiC. In addition, the dumbbell-shaped SiC whisker contributed less than straight rod-shaped SiC whisker to improving the physical properties of Al2O3-ZrO2-C materials.