Abstract: The slave station of ship energy management system（SEMS） transmitting data to master station places significant demands on the abilities of realtime and reliability.On the one hand,it requires the realtime transmission of general data frames with largecapacity,on the other hand,it must be reliable while receiving dynamic configuration frames and command frames from master station,and in turn transmitting fault record frame back to the master station.For this purpose,we proposed an Ethernet structure that could satisfy the requirements of realtime data transmission with high reliability.The structure was established by using ARM processor of CortexM3 kernel as the hardware platform,while μCOSII realtime operating system（LwIP protocol stack was transplanted） was adopted as the software platform.From communication experiments,the proposed scheme proovides good realtime and reliability,and achieves different requirements for transmitting different data frames in SEMS.