Cordierite-based glass/ceramic composites reinforced with different volume fractions of carbon nano-tubes were successfully prepared by isostatic pressing. Results showed the increase of flexural strength and fracture toughness of cordierite-based glass/carbon nano-tube composites with carbon nano-tube content. By incorporation of 5 vol.% carbon nano-tubes, the flexural strength and fracture toughness of the composites were increased by up to 50% and 72% compared to the unreinforced cordierite-based glass matrix, respectively. Scanning electron microscopy images indicated that the main strengthening and toughening mechanisms are load transfer, fiber pull out and crack bridging.