Abstract: Through the combination of geophysical work and the analysis on geological data, the geologic-geophysical models and the electrical characteristics of three groundwater reservoirs, including fault, karst cave and karst pipeline are researched. Controlled by the structure or change in erosion basis, there are multilayered karst cave and karst pipeline system in Longan County. Groundwater mainly stored in karst cave, pipeline and structural fracture. From the standpoint of geophysics, both of the fault zone and multilayered karst channel show longitudinal low-resistant band response. The groundwater reservoir filling with either water or mud that difficult to be distinguished by the resistant parameter, and therefore, we must make a meticulous analysis on the geophysical data and integrate to the hydro-geologic information. In practice, we adopt the method of mapping low resistant in high resistant area and high resistant in low resistant area to determine the location of the well, which avoids the problem of drilling into mudstone filling zone, and increased the water well completion ratio.