The exploitation of iron ore near Shawu Railway (at 40 km+870 m) has led to the overlying rock distortion and collapse above gob areas and the earth surface subsidence. Such a situation not only affects the railway transportation but also endangers the safety of lives and property of the adjacent villagers. In this study, TEM served as the primary technique and IP sounding was used to strengthen the investigation along the railway. The location, limits and spatial characteristics of the gob areas were detected through the combination of the two methods. The accuracy of the investigation was increased and the effect was fine. The exploration results can provide reliable technical support for surface safety and gob treatment, and can also supply protection to railway operation.