The tomography is a new nondestructive detection technique developed in recent years; it has special advantages of rich information

accuracy and visibility. So it has been playing more and more important role in detecting hidden danger of earth-rock dams. Based on the discussion of the theory of electrical resistivity tomography

a series of resistivity tomography nondestructive detcction tests has been carried out in Longfengshan Reservoir Dam. The seepage channels in Longfengshan Reservoir Dam has been found out; meanwhile

it has been approved that this method is reliable via applied to nondestructive detection in earth dams. The local tests indicate that the resistivity tomography nondestructive detection technique may be applied to detecting hidden dangers of earth-rock dams.