This research introduces an evolutionary design database model to describe design requirements and design results developed at different design stages from conceptual design to detailed design. In this model, the evolutionary design database is represented by a sequence of worlds corresponding to the design descriptions at different design stages. The design requirements and design results in each world are modeled using a database representation scheme that integrates both geometric descriptions and nongeometric descriptions. In each world, only the differences with its ancestor world are recorded. When the design descriptions in one world are changed, these changes are then propagated to its descendant worlds automatically. Consistency of the design descriptions in descendant worlds is also checked when design descriptions in an ancestor world are changed. A case study is conducted to show the effectiveness of this evolutionary design database model.