///The Baishuitang reservoir located in Luxi County of Yunnan Province is a medium-sized reservoir, it plays an important role in irrigation the region and flood control. While karst development in reservoir area, it has existed a leaking problem. Yunnan Province encountered extreme drought natural disaster in 2009, the reservoir was nearly dried up which cause huge economic loss. This paper provides measures for strengthening and eliminating dangers by making use of high density resistivity method to explore karst development and the trend of underground river in the reservoir area.