Abstract: Aiming at the problem that various auxiliary production systems such as video monitoring system and online monitoring system of railway transformation and distribution substation are independent of each other and lack of information interaction and unified management platform, this paper designed a comprehensive auxiliary monitoring system of railway transformation and distribution substation based on the Internet of things architecture. The system used a unified management platform and standard interface to manage video, security, online monitoring and other systems in a unified manner, implemented automatic inspection, information sharing, alarm linkage and other functions. Practice has proved that the auxiliary monitoring system breaks the phenomenon of "information island" of each subsystem, improves the operation and maintenance management efficiency of transformation and distribution substation, and reduces the working intensity of operation and maintenance personnel.