Abstract: Aircraft flexible assembly technology, due to its high assembly efficiency, precision, and flexibility, has become an essential component of the digital transformation in aviation manufacturing industry. Firstly, from the perspectives of domestic and international aviation manufacturing enterprises and universities, the research and application status of aircraft flexible assembly especially on the technologies of digital measurement, flexible docking assembly, and automatic drilling and riveting are reviewed. Secondly, three key technologies of aircraft flexible assembly are summarized, which are high-precision measurement in large space, flexible tooling and pose adjustment control, and off-line programming of automatic drilling and riveting, and the relevant theories and techniques are discussed. Finally, combining artificial intelligence with big data, digital twin, internet of things and other new technologies, the developing trend of aircraft flexible assembly are prospected. In the future, flexible assembly technology will play a greater role in improving the quality and efficiency of aircraft assembly.