Abstract: To meet reliability of rail steel flaw inspection and signal acquisition, a nondestructive testing (NDT) system based on laser ultrasonic technique(LUT) was established. The system was mainly composed of high energy pulse laser, electromagnetic ultrasonic transducer (EMAT), embedded data acquisition system and P60 rail specimens with artificial cracks. Based on analysis of Rayleigh wave detection principle, this paper focuses on impedance matching method of EMAT probe coil. Besides, working flow path and signal processing of embedded signal acquisition system were introduced. Moreover, system based LUT was used to locate the rail steel surface crack with depth no less than 0.5 mm. Finally, relationship between EMAT probe lift-off distance and signal amplitude was given.