The noncontact electromagnetic ultrasonic technology can be used to measure solidification shell thickness of slab in continuous casting. The casting technical parameters (e.g., rolling force, water sprays control, rolling location and rolling speed) can be adjusted in time to avoid central segregation and loose problems. The listed advantages have important application value for engineering. To improve the range resolution and signal noise ratio (SNR) of the electromagnetic acoustic transducer (EMAT) used in high temperature casting slab with coarse grains and surface oscillation marks, a finite element model for the testing process of a racetrack spiral coil EMAT with a chirp wave transmitting pulse is proposed. The influences of EMAT design parameters, pulse width and bandwidth of the chirp signal on the range resolution and SNR of the received ultrasonic waves after pulse compression are analyzed. Subsequently, simulation results are verified by experiments. Results show that the SNR of the received ultrasonic wave with chirp pulse compression can be improved by approximately 19 dB, and the pulse width is reduced more than 624%. Pulse width of chirp wave and magnet dimensions have significant influence on SNR. The range resolution of ultrasonic wave is affected by the bandwidth of chirp wave and magnet spacing and width. In addition, the conductor diameter of the racetrack spiral coil and its impedance matching parameters also affect the range resolution.