A method of waved-thermal field chemical vapor infiltration was introduced. And interphases of silicon carbide layer and carbon layer were processed via the route. The preforms with the interfacial coatings were densified by method of forced-flow thermal-gradient chemical vapor infiltration (FCVI) employing hexamethyldisilazane (HMDS) as precursor material of the matrix. The matrix of the composites annealed at 1400°C consists of nano-polycrystalline silicon carbide. The configuration of fracture surface was observed by scanning electronic microscopy (SEM). The interphases behaved successfully as mechanical fuse for the reinforcing fibers.