Abstract: Tunnel invert is the main structure bearing the train load, and its insufficient thickness is one of the more serious defects in railway tunnel quality detection. Therefore, in view of the shortcomings of the common core drilling method and geological radar method in detection of tunnel invert thickness, and based on the dispersion characteristics of Rayleigh wave, the experimental study is carried out for the application of Rayleigh wave method in detecting invert thickness of railway tunnels. Some suggestions are put forward in terms of the relevant parameters of the observation system and the parameters of excited dominant frequency of the receiving system, to achieve accurate quantitative detection of the tunnel invert thickness, and the accuracy of the detection results of the Rayleigh wave method is verified by drilling holes.