It described the mechanism of ultrasonic wave excitation in EMAT (electromagnet acoustic transducer), mathematical expressions of oscillation amplitude solution of ultrasonic wave in polarisation process and transduction efficiency. EMAT physical prototypes were established and multiple comparative tests based on echo magnitude were designed to investigate influence factors including excitation coils with different geometry, electromagnetic induction intensity and liftoff distance. Then, based on the test results, the corresponding influences of core functional component design on EMAT test performance were analyzed, and the test efficiency and EMAT application range in different materials were compared. Test results show that the assembly of functional components and optimization of parameter factors can improve the test performance of EMAT, which provides the basic technical reference for EMAT optimal performance design and engineering test solution.