Though CAD has become common, the studies on input systems that based on the special characteristics of architectural design process are not still enough. This paper, using a church project as the case, firstly analyzed the relationship of design changes and their respective graphic changes on the drawings, secondly reviewed the CAD procedures of graphic changes, and finally indicated facilities to be provided in the future CAD ; firstly to keep record rules of positional relations or connectivities among building elements, and secondly to adjust the size or even the shape of related elements automatically, following the recorded rules (relational operation).