Research conclusions:The study shows the seismic method along with electromagnetic method is the most effective method for exploration of the karstunder railway tunnelbecause these twomethods canwell compensate each other, the efficiency of artificial seismic source system is the key point for applying single-receiver seismic method, and the ground penetrating radar has the high resolving capability to the big-scale karsts by the data process appropriately, even under condition of the severe electromagnetic interference.