In a system which supports multi-thread,all the application programs are running in a thread-based way.Therefore,have to consider the problem of synchronization when there has the possibility that many threads accessing the same data object concurrently.The Elastos,invented by Shanghai Koretide Corporation was such a CAR technology-based operating system that supports multi-process and multi-thread,and this paper will give a presentation of how to use the extended event synchronization object to implement synchronization and message exchange among threads.