Most of companies related to the area of B2B electronic commerce are making their efforts to innovate their existing business process into new designed process. XML-based electronic data interchange has potential to impact on reshaping the traditional EDI systems. This study intends to suggest a prototype of XML-based electronic data interchange using unified modeling language, with a case study applied in Korean automobile industry. In order to accomplish the research objectives, we employed UML as its standard modeling language, In this study, four diagramming techniques such as use case diagram, sequence diagram, class diagram, component diagram among eight modeling techniques are used for analyzing hierarchical business process. As a result of applying UML methodology, we design and develop XML/EDI applications efficiently. Our field test applied to Korean automobile industry shows that data modeling to design XML application using UML is better than existing methodologies in representing object schema of XML data and in extension and interoperability of systems.