The geomembrane which is laid vertically underground has been widely used in water conservancy，building groundwork and environment engineering，etc.，to prevent seepage flow in the past 20 years in China. During being laid underground，the geomembrane may be not extend to the designable depth and be lacerated by sharp stone，maybe there are some blanks between the border upon plastics series. All those can make the seepage flow through the geomembrane. So it is important to inspect the conformation of those impervious geomembrane after they have been laid vertically underground. But 2D flimsy body laid vertically underground like this geomembrane is difficult to be inspected with the usual detection method. In order to meet this require，the two-row current and potential (CP) electrode array is designed to detect it on the base of electrostatic field theory. By theoretical analysis and field studies，the abnormal resistivity pattern of different conformation，the inspection precision of this method and the results different settings lead to have been made certain. The theoretical analysis and field study show the lower resistivity patterns in apparent resistivity section can reflects that the conformation of geomembrane and their size are corresponding；the blanks between the border upon plastics series can make the lower resistivity pattern larger；one tenth change of the depth of geomembrane and 0.1 m width of blank between the border upon plastics series could be detected with this method. The research result can make sure that the conformation of impervious geomembrane which is laid vertically underground can be detected clearly with the two-row CP electrode array.