The communication system is composed of more than one processes, which realize the functions of the system together. In most of the distributed environments, the message is the way that they are communicated a with each other. But they can not be guaranteed to arrive at the right time. In this paper, we discuss the save functions in the Specification and Description Language ( SDL) language. With these functions, a new way of transferring message can be realized reliably and efficiently. Finally, we give the simulation result according to the tools--SDT.