Abstract: At present, many enterprises have been efforts to establish a variety of computer applications in order to help business operators. While that has had a significant improvement in the efficiency， but it does not extend to companies outside the business. These businesses cover a variety of companies applications or business operations of the exchange and communication. Many cases, enterprises and their business partners, suppliers and customers there are islands of information. Between enterprises and their business partners and their exchanges are still dependent on manual processing, so efficiency is very low. Electronic Data Interchange （EDI） is considered to be the solution to this problem, and the application layer data exchange technology is the top priority of the program, this paper studies the electronic data exchange technology in applicationlevel XML data exchange technology.

Key words: XML, data exchange technology, threetier structure