There are many modules in the Emergency Rescue Simulated Training System, and information exchange between them is complex. This paper studies a set of message mechanism suitable for the simulation training system, which includes how the message is composed of message body and message type, how the message is created by message factory, message manager how to manipulate the message interacting with components, roles, and other parts. Finally, give an example for the analysis of the request synchronous message processing during the system and illustrate the relevance of messages with the system and the role it played in the system.