Conceptual　design　is　relative　to　customer　requirements,　＂taking　customer　demand　as　the　direction＂　has　already　become　the　dominant　design　concept.　The　framework　and　process　model　of　integral　conceptual　design　is　provided,　and　a　model　of　Requirement　-　Function　-　Principle　-　Structure　is　put　forward.　The　mapping　from　requirement　space　to　structure　space　is　established　by　hierarchical　automatic　reasoning　strategy,　which　integrating　case-based　reasoning,　data　mining　tool　with　knowledge　base,　thus　make　the　structure　scheme　be　utmost　closed　to　the　customer＇s　real　requirement.　Finally,　a　case　study　is　presented　to　illustrate　Elk　feasibility　of　the　system.