Abstract: Knowledge representation,which is one of the key techniques in computer aided conceptual design,is studied.Behavior domain is introduced into axiomatic design （AD） as the transitional phase between functional domain and carrier （physical） domain.Extended zigzagging mapping process for the domains is proposed to establish the relationship between functions,behaviors and carriers at different levels.The models for knowledge representation,including domain structure template for a scheme and concept space for a type of products,are built respectively.The process of schemes generation based on concept space is presented.A case study for an industry sewing machine is described to illustrate the model and approach proposed in this paper.