Abstract: With the continuous promotion of the construction of new power systems, the complexity of the operating conditions of substation equipment has significantly increased, and the traditional single source data state evaluation mode is no longer suitable for the safe operation needs of the power grid. This article focuses on the research of the full chain state evaluation of substation equipment based on multi-source data fusion. It systematically analyzes its application value and equipment fault evolution characteristics, and constructs a full chain evaluation method system covering data collection, fusion processing, evaluation modeling, and decision-making application. It provides theoretical and practical support for the intelligent operation and maintenance of substation equipment.