A network structure of the feeder automation system based on 10 kV power line carrier communication is presented. The design scheme for the hardware platform of feeder terminal unit（FTU） based on ARM7 processor is illustrated， and the functions of modules in the platform are described in detail. In particular， the carrier communication module can cope with the terrible transmission characteristics. TheμC/OS-Ⅱ embedded real-time operation system is adopted in the software design scheme to perform relay protection， data acquisition， carrier communication， and wireless remote control. As no appropriate communication protocols are at present available for distribution network carrier channels， by taking into account the characteristics of the IEC 870-5-101 protocol， a communication protocol design scheme is put forward based on the finite state machine， with flexible， reliable relay communication realized. Field application shows that the proposed feeder automation system is of fairly high practical value for its stability and reliability.