The fracture of titanium matrix composite reinforced by TiC particles has been studied. The results indicate that the proportion of defective particles will significantly influence the crack propagation rate. Regular and non defective particles will not fracture easily during the initial deformation, and hence will greatly enhance the crack extension energy. On the contrary, the easily broken particles enhance the extension stress at the crack tip, and hence the propagation rate of the crack. Suitable heat treatment will increase the crack extension energy, and improve the plasticity of the composite.