Infiltration and localization of preferential infiltration zones at the dam abutment are measured using radioactive tracer tests of flow in boreholes, meanwhile interconnection between boreholes and the energing water points is analysed. The theory and practice of radioactive tracer synthetic detective method are described to give methods and calculation formulae used under the condition of stable flow in single well to measure permeability coefficient and hydrostatic heads. Major single hole techniques including measurement for seepage line, velocity, rate of seepage flow and relationship of recharge of groundwater in aquifers are introduced briefly. The possibilities offered by natural tracers are analysed, including electric-conduct, pH-value and temperature of water as well as stable isotopes (D, ¹⁸O) and tritium. Furthermore, the sensibilities of this theory and methods were confirmed by detecting seepage flow field of Xinanjiang Dam.