Abstract: In order to make the transformer protection outdoor installation, an implementation scheme of distributed transformer protection is proposed. Distributed sub protection machines, which transfer data between each other through the high-availability seamless redundancy（ HSR） bidirectional ring network, are installed for each switch of transformer. The high-voltage side sub machine integrates the main and backup protection function. After an analysis of the overall scheme, focus is on the key technologies of the ring network communication and sampling synchronization. Theoretical analysis and experimental data show that, compared with the existing centralized transformer protection device, the distributed transformer protection has definite advantages in terms of reliability and rapidity.