Abstract: Concurrent engineering is a philosophy that attempts to take into account of all the activities of a product life cycle early in the design stage. In the manufacturing industry, approximately 70% of a product`s manufacting and assembly costs are determined during the design stage. Similar to the software industry system analysis and design has significant influence on later activities of the software development life cycle. Object-oriented approach has been the main stream for software development, and unified Modeling Language (UML) integrates most of the object-oriented modeling methods and has become the standards. This paper incorporates the CE concept into the evaluation of object-oriented software development and proposes a Hierarchical Aggregation Model (HAM) to early evaluate the object-oriented software design quality based on UML. There are three advantages of using this model. First, this model can help reduce the project risk, cost, and time span, and eventually improve the software quality early in the software development life cycle. Secondly, this model facilitates the use of the standards of object-oriented modeling language, UML, which makes proposed model more applicable to real software development. Thirdly, this model is easy to implement, that can potentially be imbedded in CASE tools to directly support the project manager`s decision making.