Abstract: This paper presents a generative feature based design methodology that supports modifying feature-based model in a localized way.Feature′s shape is swept by sketched profile.A floating datum system is built up to guide the feature definition.A feature can be attached to other feature or product model through this floating datum system.Object entities to which the datum is attached can be deleted,but the datum and the related features are still existing,and temporarily floating in the work space.Thus features can be freely modified,cut out and relocated,or deleted in a localized way.