Using GPRMax basd on the theory of finite difference time domain (FDTD), and taking into account three different frequency antennae of 400 MHz, 900 MHz, and 1500 MHz, the author simulated the image characteristics of the ground penetrating radar reflection and interference signal obtained from the objects inside tunnel lining, including different steel mesh densities, different rebar diameters, steel arches and air layers. An experiment of ground penetrating radar survey was carried out on concrete specimen, the Kirchhoff migration was used to process the numerical simulations and experimental data, so as to suppress the diffracted wave and multiple wave coming from rebar mesh and improve range resolution of weak reflection signal under steel mesh. Based on the comparative analysis of the numerical simulation data and the experimental data on concrete specimen and tunnel lining detection results, the authors reached some conclusions which can be used as a reference for obtaining better detection results of ground penetrating radar survey in tunnel lining.