The use of self-sensing materials such as piezo-resistive cementitious materials modified by carbon nanotube (CNTs) additives may be able to achieve a potential real time structural health monitoring in structures. However, due to the small fractions of CNTs in the cementitious materials, the piezo-resistive effect for self-sensing is usually too small to be monitored accurately in field. In this study, a theoretic algorithm is developed to analyze the piezo-resistance of CNTs modified matrix with considerations of CNTs dispersing effectiveness. Three different dispersing methods were investigated using the developed algorithm to search for a method to uniformly disperse the CNTs in cementitious materials. Laboratory experiments showed that the theoretical algorithm analyzed well for all the dispersing effectiveness of the three different methods. The surfactant method is approved to be a very promising approach to disperse CNTs. Further investigation to lower the standard deviation of the co-polymer method are needed in future.