The scheme of distribution automation adopting feeder protection can isolate the fault quickly. Based on the system protection principle to distribution network， a new type of feeder terminal unit（FTU） is developed. The FTU systems use optical communication. The optical Modem disjoins the SCADA communication and Boolean signals functions using coding technology. So the fault flags can be exchanged rapidly peer-to-peer and special optical cables are not necessary. Frames between optical Modem are sent automatically. Protection function and SCADA function in the FTU are individual function modules. This FTU scheme succeeds in physical experiment and it has been put into operation for more than two years.