Abstract: The applications of typical controlled area network (CAN) protocol and time-triggered protoco l(TTP) are summarized to provide a bus framework for autonomous underwater vehicles(AUV), and some methods are suggested for the bus connection and data transmission of the future AUV. According to the application of AUV, the operational principles, reliability mechanisms, extensibilities, error treating tactics, and the system level properties of the distributed real-time systems based on CAN protocol and TTP are compared. The results show that CAN protocol is well suited for the soft real-time systems where flexibility is important, while TTP is most appropriate for the integrated hard real-time systems with higher reliability requirement.