Modeling software with the model driven architecture (MDA) concept and unified modeling language (UML) has become a new trend for the objected-oriented systems analysis and design. Several CASE tools which embed MDA concept and UML have been introduced to facilitate the transformation from platform independent model (PIM, i.e., class diagram) to platform specific model (PSM) in order to enhance the efficiency of software development. In this work, we present a systematic methodology which integrates the concept of MDA and UML with CASE tool to refine the process of UML transformation. A personnel leave prototype system is implemented to illustrate the concepts, application, and advantages of the proposed methodology. With this approach, software developers can construct the PIM efficiently and thereby enhance the efficiency of system development.