Cancer is one of the main causes of worldwide mortality, due to the absence of precise diagnostic tools for the cancer early stages. Thus, early diagnosis, which supplies important information for therapy of cancer timely, is of great prominence for propagation of cancer cells, controlling the growth of the disease, and improving of patients survival rates. To attain the goals of early diagnosis and cancer therapy timely, nanotechnology of DNA can be effective, since it has protruded as a suitable technique for the fabrication of different nanoscale devices and structures. The eventual DNA-based nanoscale devices and structures show wonderful performance in diagnosis of cancer, owing to their small sizes, structures, high programmability and biocompatibility. In particular, the quick development of DNA nanotechnologies, like molecular association technologies, confers DNA-based nanomaterials with more intellectualization and functionalization. In DNA nanotechnology, Watson-Crick DNA molecules are arranged into variety of nanostructures in the range of 10-100nm size under special physical conditions due to electrostatic attraction between free electrons of base nitrogen and phosphate oxygen and sugar. Here, i summarize recent advances made in the development of DNA nanotechnology for the fabrication of intelligent and functional nanomaterials and highlight the potentials of this technology in diagnosis and therapy of cancer