Abstract: To address the problem that the shear waves excited by conventional electromagnetic acoustic transducers (EMATs) were susceptible to interference from longitudinal waves and mode-converted waves, thereby compromising detection accuracy during corrosion inspection of the inner walls of high-temperature pressure vessels in the energy and nuclear power industries, an optimized EMAT structure method was proposed in this study, in which a copper foil shielding layer was added and the main-to-auxiliary lobe distance was adjusted to suppress the amplitude of longitudinal waves. First, an axisymmetric two-dimensional finite element model was established to simulate the static magnetic field distribution of the permanent magnet on the surface of a low-carbon steel specimen, and the relationship between the Lorentz force and the magnetic field direction in the main and auxiliary lobe regions was investigated. Subsequently, through finite element simulation and experiments, the influence mechanisms of the copper foil shielding layer and the main-to-auxiliary lobe coil spacing on the Lorentz force distribution, ultrasonic excitation types, and shear wave signal purity were explored.The results indicate that compared to the traditional spiral coil and the single-layer butterfly coil, the optimized double-layer butterfly coil design achieves an increase in shear wave amplitude by factors of 2.46 and 1.43, respectively. The amplitude ratio of shear wave to longitudinal wave is enhanced by more than two times, while the highest signal-to-noise ratio reaches 25.82 dB. By effectively suppressing the longitudinal wave amplitude and enhancing the purity of the shear wave, a new high-performance EMAT solution for corrosion detection in high-temperature pressure vessels is provided in this study.