Abstract: This paper provides a comprehensive review of the 75-year development of reactor engineering technology at the China Institute of Atomic Energy (CIAE). Since its founding in 1950, CIAE has played a pivotal role in the evolution of China’s reactor technologies—from initial establishment to technological maturity and leadership. The CIAE has successively designed and constructed a series of research reactors, including the 101 reactor, the 49-2 reactor, and a lot of zero power reactors, marking a progression from foundational breakthroughs in nuclear science to the establishment of a complete reactor engineering system, and eventually to the forefront of advanced nuclear energy technologies. Significant innovations have been achieved in reactor physics, materials science, and operational technologies, enabling wide-ranging applications in neutron science, nuclear medicine, precision manufacturing, and other high-tech domains, thereby providing strong support for national strategic objectives. Today, the convergence of artificial intelligence (AI) and reactor technology presents transformative opportunities, and CIAE is actively engaged in interdisciplinary research to drive the intelligent evolution of reactor systems. Through decades of sustained innovation, China’s reactor engineering capability has transitioned from a phase of technological adoption to leadership in key areas, and continued integration of AI is expected to further accelerate progress and contribute meaningfully to the advancement of the nuclear energy sector.