Abstract: In this paper, the problem using electromagnetic ultrasonic shear wave to measure continuous casting shell thickness at the end of secondary cooling zone is studied, and the finite element simulation model is established. A Q235 continuous casting billet is selected as the tested object. In order to reduce the lift distance of the permanent magnet and generate larger induced eddy current in the measured body, a simulation model of the electromagnetic ultrasonic transducer (EMAT) different from the general structure is established by using the multi physical field finite element simulation software. In this structure, two spiral coils are arranged in parallel on both sides of a cylindrical permanent magnet. The influence of the size of the permanent magnet on the eddy current of the magnetic field and the propagation of the electromagnetic ultrasonic shear wave in the billet at different times and positions are analyzed. The magnetic flux density modulus and current density modulus in the measured body are calculated, and the eddy current size and particle displacement are also calculated. The results show that the electromagnetic ultrasonic transducer with this structure can successfully excite and receive the electromagnetic ultrasonic shear wave on the surface of the continuous casting shell; the shear wave has strong penetration and high efficiency, it can successfully detect the echo signal and calculate the shell thickness of continuous casting billet.