Textbook in PDF format As an important development direction of flight vehicle system engineering and integrated design, MDO method fully considers the coupling effect between multiple disciplines of flight vehicle system, improves design effect and reduces development cost through collaborative tapping, and enhances design efficiency through high integration and automation of design tools of multiple disciplines. Since its inception in the early 1980s, MDO method for flight vehicle has been developed for more than 40 years, creating systematic theoretical methods, tools and software and application verification results. Furthermore, MDO method has been promoted and applied from aerospace to vehicles, ships and other fields, generating huge economic and social benefits