By adding the macro steel fiber (SF),the carbon fiber (CF) and the nano-carbon black (NCB) into the concrete as the multiphase conductive materials,the influences of the SF,the CF and the NCB on the mechani- cal properties and conductivity of the cracked concrete as well as on the self-monitoring performance of the crack development are investigated.Then,a relationship between the fractional change of the surface resistance (FCR) and the crack opening displacement (COD) of the conductive concrete beams is established.The results show that (1) the addition of the conductive materials can greatly enhance the flexural strength and toughness of the con- crete; (2) the hybrid use of the NCB,the CF and the SF shows a clear positive hybrid effect on the flexural beha- vior and the self-monitoring performance of the crack development; and (3) there is a linear relationship between the FCRand the COD.