Abstract: This paper gives a brief overview of the development on the inverse problem of flaw detection. Several typical identification methods are discussed, such as, the electric method based on the potential principle, the boundary element method with optimization iterative technique, the theory of diffraction, the translation matrix method, the Born approximation theory, the boundary integration equation and the boundary element method. Some of the author'[KG-*2/3〗s new contributions in this field is introduced a...