Mobile agent (MA) is an offspring of distributed technology combined with agent technology and it is a intelligent agent with mobility. So it has good application potential in distributed network. The appearance and characteristics of mobile agent are presented, and then three standards and criterion related to the mobile agent are summarized. Five representational mobile agent platform (MAP) are discussed and their communication paradigm and structure, providing service and characteristics are compared. Finally, the application potential, deficiencies of current research and the possible trend of mobile agent technology (MAT) are discussed.