Abstract The relationship between multidisciplinary design optimization (MDO) for aircrafts and the large-scale system theory was expatiated. Using the large-scale system theory, the system was decomposed gradually based on the different classification standards and the system characteristics. At the same time, the MDO methods for aircrafts were classified according to the decomposition-coordination method of the large-scale system theory. The theory background and applicable range of each algorithm were elucidated. Aircraft design system is a typical engineering large-scale system, and the basic of MDO for aircrafts is the large-scale system theory. Therefore, the large-scale system theory and MDO for aircrafts should be studied simultaneously to improve the MDO.