The alpha-card measurement is a new kind of nuclear technique to evaluate the concertration of the radium and thorium emanations with a short-time accumulation. It has shown the wonderful characteristics of higher sensitivity

greater detective depth

less interference and shorter work period when applied to search underground water resources in bedrock. The satisfactory result of its application in Pingyin limestone area is described. The principle of the alpha-card measurement and the foundation of its application are briefly discussed.