With case studies this paper deals with the application of geophysical prospecting to geologic calamity investigation and water exploration.During the leakage investigation of the Wenxiakou reservoir, radio wave penetration method and "mise-a-la-masse" method were successfully used to locate leakage channel; during the investigation of the dirsction of Yemaodong cave at the Pengshui dam site of the Wujiang River, the direction of the karst channel buried some 100 m at depth was found out by means of radio wave penetration method; to look into the leakage that occurred along the batardeau of the upper reaches of the two rivers at Gezhouba dam, self-potential method was used and, as a result, leakage position was accurately located.Concerning water exploration in Quaternary sediments, two examples are presented which deal with the application of D. C. electrical sounding.Finally, the paper mentions some problems that are worth noticing in the application of geophysical prospecting to geologic calamity investigation and water exploration.