The monitoring of rail safety status is crucial to ensure the safe operation of trains. Aiming at rail crack detection, this study quantitatively compares different crack detection technologies and analyzes the application of infrared thermal imaging technology in rail crack detection. The proposed detection technology comprises three parts: external excitation heating, infrared image acquisition and image processing. Firstly, the common excitation methods are introduced and compared. The application of halogen lamps as excitation sources in crack detection is described in detail. Secondly, a halogen lamp excitation based infrared thermal imaging detection experimental platform is developed. Thirdly, an improved image processing algorithm is proposed to enhance the collected infrared image. Finally, this study discusses the prospects of applying the proposed technology in the future.