Abstract: Mobile agent will be one of the major modes of network computing in the future. The migration mechanism, the core technology of mobile agent, catches widely attention from both industry and academy. After surveying some representative approaches to migration models used in mobile agent systems, a new structured migration mechanism is proposed, which supports explicit separation of itinerary scheme from the mobile agent and completely explicit structured expression of itinerary scheme, so that the complexity of mobile agents is controlled and the reusability is supported. This mechanism has been implemented in the self-designed mobile agent system Mogent 2.0.