Alumina reinforced SiC particles and whiskers composites having high crack-healing ability and fracture toughness were prepared. The crack-healing behavior was systematically investigated. From the obtained results, the mechanisms of the composites were studied. For the crack-healing by SiC whiskers alone, partial bonds were formed by connecting between the crack surface and the bridging SiC whiskers. As a result, the crack-healed part has low reliability although the strength is sufficiently recovered by crack-healing. On the contrary, alumina/SiC particles/SiC whiskers multi-composite could form the crack-healed part having high reliability, as the space between the crack surfaces was completely filled with the formed oxide.