Corrosion potential, corrosion current density and AC impedance spectroscopy were applied to study the efficiency of cathodic protection to steel in concrete structures with carbon nanotube carbon fiber(CNT CF) cement based materials overlay auxiliary anodes. Test results show that the applied electric current could cause enough negative potential shift and provide effective protection to steel. Compared to carbon fiber cement based materials, corrosion current density of cathodic protection specimens with CNT CF cement based materials overlay as auxiliary anodes is smaller and the protective effect is better. The capacitive loop diameter of Nyquist figure in the intermediate frequency region and the charge transfer resistance of specimen under cathodic protection both increase. Using CNT CF cement based materials overlay as auxiliary anodes has a prominent effect on cathodic protection of steel in concrete structures.