Abstract: The switch rail is prone to breakage under its periodic load, causing train accidents. In order to detect the defects of the switch rail, a guided wave detection system based on the magnetostrictive effect is developed, and the related issues, such as the propagation characteristics of the guided wave in the switch rail, the detection ability of the guided wave to the accessories of switch rail and the ability to identify the defects, are studied. The ABAQUS/Explicit finite element method is used to study the propagation characteristics of guided waves with different frequencies in the switch rail. The developed magnetostrictive guided wave detection system is feasible and effective for detection on the switch rail. By the guided wave detection system, the horizontal shear guided wave excited on the bottom surface of the switch rail can travel an effective distance of at least 12 m in the basic rail and the switch rail, and at least 16 m in the empty rail. Moreover, the low-frequency guided wave mainly propagates along the bottom of the rail, and the highfrequency guided wave mainly propagates along the rail waist and the rail head. The combination of multi-frequency guided waves can more accurately realize the detection (monitoring) of the switch rail.