The multiply reinforced mullite-zirconia composites were prepared with addition of Al2O3 particles, platelets, and fibers. The sinter-HIP specimens (presintered at 1$700^{circ}C$ and hipped at 1$600^{circ}C$) showed that the fracture toughness of Al2O3 fiber reinforcement (4.4 MPa.{{{{ SQRT {m} }}) was higher than those of platelet (4.0 MPa.{{{{ SQRT {m} }}) and of particle (3.9MPa.{{{{ SQRT {m} }}) reinforcement, whereas the fracture strength of Al2O3 particle reinforcement (304 MPa) was higher than those of platelet (293MPa) and of fiber (248MPa) reinforcement.