The power system is evolving from a unidirectional chain of "production-transmission-consumption" to a new, interactive, and multi-directionally coordinated power system featuring "source-grid-load-storage" interactivity. In this transformation, data has become the core coordinator and value-driven engine. This paper takes power grid companies as an example, analyzes the characteristics and value sources of data assets, as well as the mechanism by which data affects enterprise value, and on this basis, establishes a value assessment model for data assets. Power big data is characterized by large scale, strong real-time performance and high quality, and has great application value. A thorough understanding of the characteristics and value of power big data not only helps power grid companies optimize their data management strategies, enhance the safety, reliability and economy of power grid operation, better meet user needs and cope with complex operating environments, but also improves social service and management levels through applications in external fields such as economic analysis, social governance and industrial supervision.