Abstract: The features of engineering CAD expert system are discussed, and an ADDES system(Aircraft Drawing-Die design CAD Expert System) is built.Based on the building of DIE coding system,the feature-based code method etc.are used to build user model. The agents in the system have the ability to solve partial problem, and the system organizes the agents into distrib-uted and hierach ic al form. The system synthetical ly uti lizes blackboard s tructure,meta-rea-soning and so on to control the problem- solving process.As discussed above,the problems such as low efficiency etc. caused by building big knowledge base can be solved andt he cooperation of many expert systems can be reached

Key words: computer aided design, expert systems, knowledge bases artificial intelligence