Abstract: In order to reduce the number of magnets of multi-channel electromagnetic ultrasonic transducer and improve the signal-to-noise ratio of detection signal, a combined magnet structure EMAT (electromagnetic acoustic transducer) is proposed. Using this EMAT, ultrasonic thickness measurement, axial guided wave and circumferential guided wave scanning can be completed in one detection process. The structural design of the transducer is optimized by simulation, and the influence of its structural parameters on the magnetic field intensity is analyzed. The transducer is designed and the test platform is built to verify the correctness of the model structure. Compared with the excitation effect of the traditional transducer, the magnetic field intensity generated by the transducer near the surface of the workpiece is relatively strong, and the thickness measurement and guided wave scanning in both axial and circumferential directions can be completed at the same time. The signal-to-noise ratio of thickness measurement signal is increased by 2 dB, the signal-to-noise ratio of guided wave signal is increased by 19. 5%, and the detection efficiency is improved.