In the karst zones of Southwest China, groundwater is mainly stored in karst caves, karst channels and fractures. In the work practice of fighting a drought and finding water in Long’an County, the authors estimated the location of water-bearing structure on the basis of geographic and geomorphic conditions, formation lithology, distribution of ponors and spring spots, then determined a target range for finding water. Furthermore, the authors described the spatial characters and watery property of ground water reservoirs in terms of resistivity response of water-bearing structure and hydrogeological information.