In recent years, broadband access is developing with astonishing speed. At the same time, the mobile Internet technology is also increasingly mature, instant messaging business have become a hot point of the era of mobile Internet applications. XMPP and SIMPLE are widely used in the Internet, but they are not suited to the mobile Internet. The MQTT is a publish/subscribe model based and lightweight messaging protocol, which has the advantages of reducing power consumption, decreasing flow and has strong flexibility. Firstly, this article analyzes the shortcomings of XMPP and SIMPLE protocol. Secondly, it introduces the message format and the usage of the MQTT protocol. After the design and implementation of the instant messaging business, the related testing and analysis are carried on the function and performance.