With　the　rapid　advancement　of　wireless　network　technologies,　Mobile　Instant　Messaging　(IM)　has　become　a　major　application　in　the　telecommunications　industry.　Firstly,　this　paper　introduces　recent　research　and　development　efforts　in　constructing　mobile　IM　systems.　Secondly,　it　advances　a　new　service　model　and　implementation　mechanism　based　on　Jabber/XMPP.　The　communication　protocol　of　our　system　provides　an　open,　expandable,　real-time　communication　technology　that　can　be　used　to　build　a　wide　range　of　XML　applications.　The　system　can　build　stable　and　efficient　mobile　IM　service　that　covers　multimedia　content　sharing　and　corresponds　with　external　services　conveniently.　It　can　also　flexibly　respond　mobile　IM　requests.　The　system　uses　the　newest　network　technology　to　supply　WAP　access　and　provide　Web　services.　Owing　to　these　features,　our　design　model　and　implementation　mechanism　may　satisfy　rapidly　increasing　and　changing　requirements.