Applying the integrated electrical method comprising such means as vertical electric sounding, sounding of induced polarization and transient electromagnetic sounding, in combination with the regional hydrogeological conditions, the authors conducted underground water exploration in the piedmont water-deficient region of the Qilian Mountains in Hexi corridor, which had been regarded as water-poor or no water area by previous workers. As a result, extensive water-bearing layers characterized by high apparent resistivity were found in great thickness of deep Quaternary clay sediments and Tertiary mudstone beds. More than twenty hydrogeological drill holes confirm that inflow of water per well is greater than 2 000 cubic meter per day, mineralization of water is less than 1.0 gram per liter and success rate for arrangement of wells is higher than 95 per cent. The work conducted by the authors has not only completely solved the problem of drinking water sources in this region but also accumulated a wealth of experience for underground water exploration in similar regions. It yields notable social benefits and also has a certain research value.