Abstract: With regard to complex diseases of composite linings of railway tunnels, a specimen model for composite linings in terms of the whole size is established, and the ground penetrating radar (GPR) detection is studied based on simulation tests. The test results show that lining abnormalities can be reflected, which are pre-set in the GPR scan, with the typical characteristics of the strong reflection zone and a continuous phase axis. The measurement accuracy of the secondary lining thickness relates to the relative dielectric, the thickness of the secondary linings can be analyzed by quantitative analysis under the conditions that the relative dielectric of layer is accurately determined, and the accuracy can reach ? 4cm. The relative dielectric should take the average number of gauge point, and the linings of plain concrete and reinforced concrete should be determined separately. The results will be valuable for the results of GPR detection in actual engineering.