In this paper，the authors first discuss the structure and functions of the knowledge—based computer—aided exam—paper formation and analysis system shell，and than present the tactics of“indexes—directed”knowledge acquisition and the structure and representation methods of the knowledge base，and then introduce the inference mech-anism of exam—paper design as well as the“exam—paper pattern—oriented”solving mod-el、the layered random selecting and conflict—solvi“g rules．