After well-known structured technology, object-oriented technology has become another paradigm of system development and a hot topic in the field of software engineering. The Unified Modeling Language (UML) has become a standard means for the analysis and design of object-oriented after it passed the certification of the Object Management Group (OMG) in 1997, and it was widely used in many industries. Although it becomes a standard of object-oriented modeling language, UML hasn¡¦t provided principles or guidelines for mapping classes to tables. The purpose of this study is to investigate the guidelines for transforming UML class diagram to object-relational model. The transferring methods include both static structure transfer and dynamic behavior transfer. An example of automobile ordering system is used to illustrate the guideline and application. With these guidelines, analysts can easily use the UML class diagram to express database designing and thereby improve the efficiency and effectiveness of UML modeling.