Abstract: Cement-based material is an inert material with high electrical resistivity, but its electrical conductivity can be obviously improved by the addition of short carbon fibers (0.2 vol%~ 1.2 vol%). In this paper, the relationships between inner microstructure and apparent electrical properties, change of electrical resistivity and external applied load of carbon fiber reinforced cement-based material were investigated. The test results indicated that the carbon fiber reinforced cement-based material could function as a smart material for the real time diagnosis of damage. The electrical signal is related to an increase in the material's volume resistivity during the crack generation or propagation and a decrease in the resistivity during crack closure. The linearity between the electrical resistance change and the applied load was good for the carbon fiber reinforced cement-based material. In contrast, the cement-based material without carbon fibers showed no variation of the resistivity during the entire load process. The change of electrical characteristics reflects large numbers of information of inner damage of the cement-based material, which can be used to detect potential damage and to prevent fatal failure.