Surface cracks in the impervious concrete panel of a concrete faced rockfill dam were examined by employing several non-destructive testing methods, including ground penetrating radar, impact echo and ultrasonic plane inspection. The characteristics of electromagnetic response of different types of cracks were analyzed, the effects and influencing factors of impact echo and ultrasonic plane measurement upon different cracks were assessed with error analysis. By comparing with direct drilling results, the effectiveness and accuracy of integrated non-destructive method, which was established by incorporating holistic rapid inspecting and local accurate measurement, were discussed in crack detection. The results indicate that ground penetrating radar, with its intuitive and high efficiency, can achieve an overall investigation of impervious panel cracks, and quickly indentify their distribution and physical properties. The impact echo and ultrasonic plane mearsuring method, with their accuracy and flexibility, can further determine the crack depth. Through reasonably combining testing methods and scientifically laying out survey lines, the proposed methods can identify the distribution, basic properties, scope and size of cracks, whilst improving the comprehensiveness, accuracy and precision of detection.