Abstract: The EMI technique, as a structural damage detection (SDD) technique, has been successfully applied in fields of aviation, mechanical engineering and civil engineering. However, compared with its application in recent years, the study on the theory and numeric is lagged behind. To avoid the theoretical lack in the application of EMI technique, in this paper, the author puts forward a new coupled model of #x0201c;PZT chip-adhesive layer-main structure (PAS)#x0201d;, which bases on recent several PAS models. By constructing the assumptions of the simplified model and deducing the overall procedure of theoretical calculation, we get the admittance formulation. This new EMI coupled model has a higher degree of accuracy and considers more factors including damping, which provides a reference for deeper theoretical study of EMI technique and a new clue for further study.