Abstract: This paper is based on the karst area of geotechnical engineering. It uses the difference in physical characteristic of the rack and soil and the wave impedance and resistivity differences. It comparatively analyses the high density resistivity method, the transient electromagnetic method, the geological radar method and other geophysical prospecting methods. Finally it determines the high-density electrical method, the seismic imaging method, the acoustic logging and drilling CT methods, as well as the surface and subsurface geophysical exploration methods to detect the site conditions of combining the karst distribution and the development conditions.