本文首先综述了即时通信的发展状况，列举了一些研究成果的应用，介绍即时通信系统的工作原理；其次分析了即时通信系统的各功能模块和软件层次结构，同时分析了即时通信软件面临的一些安全威胁；最后就目前的发展状况预测未来即时通信软件的发展趋势。-This paper summarizes the development of real-time communication, cited a number of research applications, introduces instant messaging system works　followed by analysis of the instant messaging system functional modules and software hierarchy also analyzed face some instant messaging software security threats　finally on the current state of development to predict the future development trend of instant messaging software.