Abstract: Large irregular multi-chambers steel reinforced concrete (SRC) structures have been widely employed in super high-rise buildings, and the bonding condition between concrete and steel plate is critical. In this paper, the interfacial debonding defect between concrete and steel plate in a complex multi-chamber SRC column is mimicked artificially. With PZT patches surface-bonded on steel plate, the impedance of electromechanical coupled system composed by piezoelectric material and structure is measured. The measurement results of PZT patches in both debonding areas and healthy areas of the interface are compared, and the root mean square deviation (ERMSD) is defined as a damage index to describe the bonding condition of the interface. Results show the figures of PZT impedance in interface debonding areas are quite different from those in healthy areas and PZT impedance measurement based damage index can effectively detect the inaccessible interface debonding defects.