Abstract: Researches on the information system integration are of academic and practical value for enterprise application integration. Service oriented event driven architecture (SOEDA) is proposed for constructing flexible, distributed information integration platform. Taking the form of service unit (SU), multiple adapters are designed to encapsulate various heterogeneous information systems within enterprise into information integration system. SU is service oriented component, with standard service interface, which wraps details of information process on legacy system and behaves as uniform information resource. Distributed normalized message router (DNMR) is presented as a basic platform for SU registration, discovery, and communication. Hierarchical architecture and module pattern are used to improve agility, interoperability, and integration ability of application systems and to support efficient operation on massive information. Independent running of SU enhances stability and extensibility of the information integration system. Technologies, such as event-driven model and dynamic thread pool, are introduced in SU to ensure high performance of the system and robustness while in heavy load conditions. Taking into consideration the system external load, thread cost, and resource conflicts, the efficiency of the SOEDA is evaluated based on classical queue theory. The example demonstrates that SynchroESB, built with SOEDA, enables flexible information integration with legacy enterprise systems and provides services with high efficiency and reliability.