During the foundation pile construction, the detection of concealed karst caves and other harmful geological conditions in the limestone body within an area of three times the pile diameter at the pile end is of important practical significance in deciding the ending of the drilling and pouring the foundation pile. With the seismic reflection wave method as the theoretical basis and the single transmitting and single receiving seismic exploration and foundation pile test technique as the in-situ working means, the authors, incorporating the interpretation experience of exploration data, deal in brief with the application of the above technology to the exploration of pile end limestone in a certain construction site and its verification result. The achievements made by the authors provide a valuable method and technique for solving similar problems in future.