Techniques on heterogeneous database have been concerned in the area of database research. The rapid development of the Internet brings about a problem that how to effectively connect different types of databases and application systems which are geographically distributed, automatically managed, and founded on heterogeneous models. It is an important subject. Meanwhile, the phenomenon of heterogeneous database has become common. Research on a new platform to link heterogeneous database will make sense both in theory and in the practical applications. Based on the mapping techniques of O/R and relation-database/XML, a great deal of analytical work is done. And then a set of mapping standards between Java objects and relational database is drawn up. A new method is put forward to connect various databases. The method using of XML, Java and mapping technique, makes the various data sources to be encapsulated, and not only brings more flexibility of operational flows but also provides a data access interface that is more unified and transparent. With the interface, no changes of the code will be done when the application system is connected with different databases. In this thesis, the status of heterogeneous database and major problems at domestic and abroad is analyzed. Then it presents the design of heterogeneous database connection system of Nor-west Star Company’s Infrastructure Application Platform by using XML, JAVA and O/R mapping technique. A brief introduction of each function module in system and its internal transaction sequence is followed. And the detail design and implement of key parts in each module is also given. The final part of this thesis is the conclusion of the whole system and the outlook of future works.