Through the review of history of CAD and CAAD technology development,combined with the application condition of CAAD technology in architectural design,this paper analyzes the theory and advantage of Virtual Building design,dissertates the development trend of computer aided architectural design(CAAD).The Virtual Building model is a complete database including all of the building information,which can be applied in the whole building industry such as building design,structural design,facility management,costing etc.,so as to manage all of the information during the building's life circle.