The invention relates to the technology of evaluating the state of electric transmission and transformation equipment, in particular to a system for evaluating the state of the electric transmission and transformation equipment based on a bus topology structure. The system solves the problem that a system capable of evaluating the operating state of the electric transmission and transformation equipment in real time and making maintenance decisions according to evaluation results does not exist at present. The system comprises a radar position finder, an overhead line temperature detector, an insulator contamination detector, a transformer oil detector, a power quality detector, a transformer neutral point current detector, a partial discharge detector, a dielectric loss detector, a winding temperature detector, a leakage current detector, a micro-water content detector, a data bus, a data processing module, an online early warning module, an intelligent diagnosis module, a state evaluation module, a risk predication module and a maintenance decision module. The system is suitable for power grids.