Abstract: In order to meet the rapidly growing and changing needs of mobile instant messaging,this paper provides a new service model and implementation mechanism based on Jabber/XMPP and hierarchical thinking.The protocol of model provides an open,expandable,real-time communication technology,which is used to build a wide range of XML applications.We use Linux C++,MySQL,thread pool,and protocol conversion technology to develop the services of server and use J2ME technology to develop mobile client software.The system has used the newest network technology to supply WAP access and provide web services.It is demonstrated by experiment that the system based on the model can build stable and efficient mobile IM service that covers multimedia content sharing and corresponds with external services conveniently.It processes a message at an average of 5 milliseconds and its error rate is one ten thousandth.