This experimental study was intended to improve the strength properties of Multi-walled Carbon Nano-tubes (MWCNT) reinforced cementitious composites. CNT is a very promising construction material with excellent mechanical properties. However, the strong van der Waals force between their particles hinders their dispersion, limiting strength development. Therefore, homogeneous dispersion is required to obtain enhanced strength of composites by incorporating MWCNT. With this purpose, the variables considered in this study are the level of sonication, the amount of surfactant, the replacement ratio of silica fume, etc. Studies through an optical microscope indicated that the fiber dispersion of CNT was improved with the increase of sonication period, and that compressive strength was enhanced as the degree of sonication increased. When superplasticizer as a surfactant had a SP/CNT ratio of 4∼6, the best improvement in strength was obtained. Silica fume was shown to produce the highest compressive strength at 10% replacement.