Abstract: This paper takes a slate tunnel of Xiangli expressway as the research background, through the comparison analysis of ground penetrating radar image, excavation verification and geological sketch of tunnel face, the characteristics of ground penetrating radar image under the four circumstances of the rock mass being complete, relatively broken, broken and rich in water are summarized in slate tunnel. The interpretation accuracy of advanced geological prediction of slate tunnel is improved, which provides a reference basis for advanced geological prediction and guides the construction of slate tunnel.