Carbon nanotubes (CNTs) have attracted great attention due to their remarkable mechanical and electrical properties. Incorporation of CNTs can significantly improve the properties of cement-based materials, especially the electrical conductivity. However, agglomeration of CNTs is frequently encountered which can largely weaken the functionality of composites. In this work, enhanced dispersion of carbon nanotubes in cement-based materials has been achieved by using three dispersants and in combination with ultrasonic vibration. The influence of dispersants on the electrical conductivity and mechanical properties of cement paste incorporated with CNTs has been investigated. It is shown that enhanced dispersion of CNTs achieved by the use of dispersants significantly improves the electrical conductivity through the formation of electrical networks in the cement-based composite at mature stage. Air bubbles introduced by the dispersant in cement-based composites reduces its electrical conductivity significantly. Moreover, the air bubbles also lead to a large decrease of the compressive strength of CNTs reinforced cement-based composites.