Abstract: In order to evaluate such characteristics as weight and static stability of proposed concepts effectively and conveniently during aircraft conceptual design, the implementation of center of gravity and associated weight estimation in an computer aided aircraft conceptual design system, whose data organization is object oriented, was studied. The emphases were placed on the object oriented structure of center of gravity estimation and methods adopted in this part, especially the methods of estimating center of gravities of fuel and landing gear based on the design and modeling of relevant components. Through conducting weight and center of gravity estimation during the process of dynamic adjustment of concepts, the adaptability and reliability of this part, as well as the flexibility of designers’ interactive controls on estimation, were validated.