The fracture toughnesses of nanometer she Zro2 Particles toughening MoSi2 mains compositesmade by hot-pressing have been calculated by the various equations, and the effects of indentatinn loads onK1c values of the composites have been also investigated. It is demonstrated that the K1c values of test material do not abide by the median crack system equation and abide by palmquist crack system equeations. Theindependent fracture toughness from indentation load at room temperature has been observed in this material.