The role of interface on the fracture toughness of ceramic glass reinforced with metallic ribbon was investigated. A strong interfacial bonding strength is essential for load transfer between the matrix and ribbon, and for utilization of the ductility of the reinforcement. However, weak interfacial bonding is considered to be important so that ribbon pull-out can improve the toughness of brittle ceramic matrix composites. The main aim of the present study is to carry out interface design to optimize mechanical properties of brittle ceramic matrix composites reinforced with ductile metallic ribbons.