Abstract: Tall building structure CAD system is studied in an object-oriented analysis method. While a series of basic objects and decomposition, relation, action among these objects are carried out, an object-oriented model of tall building structure is established in this paper by object-oriented design method. By combining object-oriented modeling technique with relation database approach, a tall building engineering database is constructed and established preliminarily. This engineering database can effectively organize and manage the data of the tall building structure integration CAD system.