The　matter-element　extension　method　is　a　new　method.　This　study　combines　its　ideas　into　different　aspects　of　product　design,　and　combines　theory　with　practice　through　a　simple　and　clear　application　form.　Through　the　results　of　this　research,　people　who　are　engaged　in　product　concept　innovation　are　provided;　or　those　who　want　to　apply　the　matter-element　extension　method　for　research　are　followed.　In　this　study,　cat　nail　scissors　were　selected　as　the　case　study　of　extension　design.　From　the　function　and　principle　analysis　of　general　product　conceptual　design,　with　the　advantages　of　extension　method　in　knowledge　representation　and　reasoning,　a　series　of　design　cases　were　circulated,　and　finally　the　convergence　was　concluded.　An　innovative　cat　nail　clipper.