Abstract: In order to find out the medium structure and hidden danger of the main diversion channel in Fukang section of Yin-Er-Ji-Ke Water transfer Project, the multi-electrode resistivity method and geological radar were used to conduct comprehensive investigation, and the location, shape and scope of four unstable settlement areas were identified. The reliability of the detection effect was verified by surface excavation project. Engineering examples show that the multi-electrode resistivity method can directly reflect the distribution characteristics of geoelectric section, and the sudden change of resistivity is easy to identify leakage hazards. Geological radar imaging is accurate and intuitive in wave impedance level and identification of heterogeneous media, which can effectively supplement the multi-electrode resistivity method. The combination of the two methods, using multiple parameters to improve the accuracy of anomaly identification, reduce the multi-solution of geophysical anomalies, combined with a small amount of engineering verification, can play an important role in the detection of hidden seepage of dam foundation such as channels, reservoirs, flood prevention levees and so on.