Fault diagnosis and self-healing of the distribution network play an important role in the safe operation and reliability of the distribution network. Firstly, the system architecture of fault diagnosis and self - healing of intelligent distribution network is put forward, and the advantages of the protection system architecture are analyzed. At the same time, the functional requirements of the advanced FTU are put forward. And then put forward the principle of face protection fault handling, including three parts namely fault location, fault isolation and fault recovery. Finally, the effectiveness and applicability of the proposed protection system are verified by field test.