As an important part of intelligent substation, the substation state monitoring system can provide real-time online monitoring of important parameters of the main primary equipment such as transformers, composite apparatus, and arresters in the substation via condition monitoring unit, so as to provide basic data support for equipment management in power grid. The online monitoring solution for substation system includes dissolved gas monitoring in oil, partial discharge monitoring, insulation monitoring and other monitoring measures, which analyzes and processes the state data and information in real time, assists in preliminary decision-making, and realizes the self-diagnosis function of intelligent equipment in the station. It is an important basis for the new generation of intelligent transportation and inspection of substations.