This paper presents a new CAD prototype with artificial intelligence specially designed for bucket elevator design. This system integrates artificial intelligence into a CAD system, so the design process is different from the conventional design process, and much similar to the way human engineers solve problems. It is a case-based and rule-based reasoning system used to design mechanical products which have complex structure. Also, this paper discusses the case representation method and a fuzzy mathematics is used to choose the most similar existing design for the incoming product design. The proposed system described has been realized on a computer prototype program.