To　accurately　obtain　the　structure　schemes,　a　method　of　similarity　matching　and　reasoning　for　requirements/structure　mapping　based　on　grey　relational　theory　was　put　forward.　In　automatic　two-stage　case-based　reasoning　model　of　grey　relational　similarity　matching　and　solving,　a　hierarchical　grey　relational　solving　mapping　strategy　was　designed　to　complete　requirement　conversion　and　function　solving.　Normative　requirement/function　code　form　was　used　and　the　rules　of　preliminary　information　retrieval　were　set　to　narrow　the　scope　of　case　retrieval.　The　comparative　rules　of　differences　information　were　set　up,　and　requirements　and　functions　index　weights　were　introduced　to　the　grey　relational　grade　formula　by　matching　case　with　grey　relational　analysis.　Thus　product　conceptual　design　structure　schemes　could　be　automatically　obtained　to　make　the　reasoning　solution　fit　for　practical　application　of　conceptual　design.　The　effectiveness　and　feasibility　of　the　model　were　verified　through　applications　of　clam　harvest　machine　and　packaging　crusher.