Abstract: Electromagnetic acoustic transducer (EMAT) can be used without coupling agent, which makes it convenient to apply to ultrasonic inspection of structures under severe conditions. However, due to the complex multiphysics field energy conversion mechanism of EMAT, usually there are disadvantages such as low energy conversion efficiency and low signal-to-noise ratio of the received signal. In view of the above problems, a study of the effects of several parameters such as coil width, coil spacing and magnetostrictive patch on the energy conversion efficiency of EMAT is made in this paper, and the design of the SH electromagnetic ultrasonic transducer is optimized. The experimental results show that a certain thickness of magnetostrictive patch has a gain effect on the transduction efficiency of EMAT. Based on the sensitivity of SH0 guide wave to interface change, the optimized EMAT is used to detect the bounding performance of weakly adhesive structural parts of multilayer aluminum plates caused by curing temperature and other factors. The experimentally measured adhesive strengths are consistent with the changing trend of structural tensile strengths, which indicates that the optimized EMAT can be applied to the detection of bonded structural states.