Smart substation uses more optical cables, but an artificial way to check corresponding relation between optical cable (actual circuit) and virtual terminator circuit are inefficient and error-prone. This paper analyzes principle of corresponding relation between virtual terminator circuit and actual circuit, proposes a smart tag’s technology based on the two-dimension code, and studies the coding, generating and parsing. Through scanning the smart tag, it can display the corresponding relation between virtual terminator circuit and actual circuit, thus, reduces the error rate of optical cable maintenance, and facilitates the debugging and maintenance on the spot. The technology has been applied in 220 kV Huashan smart substation of Zhenjiang, Jiangsu province. Results show that the technology can greatly improve the efficiency and correctness of the smart substation’s debugging, maintenance and reconstruction.