Ethernet for space utilization added time-triggered protocol to a star topology network that was used for Ethernet service; moreover it was fully compatible with the standard IEEE802.3. This Ethernet can effectively solve the problems of real-time, uncertainty and reliability on communications for payload communicating through standard Ethernet. Time-triggered Ethernet was based on global reference time, and the real-time data transmission kept strict timing, supported time and event-triggered communication simultaneously. Time-triggered channel in this Ethernet was suitable for real-time synchronous or periodic message transmission, while event-triggered channel was suitable for sporadic or aperiodic message transmission. To prove the result that Ethernet can ensure the network reliability and security, enhance flexibility, and can greatly improve network availability, many work have to be done. For example, it designed an Ethernet topology and protocol stack for space utilization, described system communication process, studied time-triggered protocol, and simulated synchronization and network performance.