Abstract: Nuclear medicine is a novel technique of theranostics that uses radiopharmaceuticals. Nuclear medicine dated back to a century ago. Owing to the development of nuclear medicine devices and radiopharmaceuticals, increasing clinical demand, government support, and global cooperations, nuclear medicine has witnessed a rapid development. Nowadays, nuclear medicine has played an important and unique role in diagnosis and therapy. There are opportunities and challenges in future development of nuclear medicine, and more progress will be made in nuclear medicine imaging, radionuclide therapy, and artificial intelligence.