E.Stamping process features, function combination features and elemental features.And the hierarchical con straints network for the model is created,and its reasoning process discussed.

• 覆盖件模具特征分为冲压工艺特征、功能组合特征和基元特征三个层次，与此相应建立了分层的约束网，并叙述了其推理过程。