Abstract: The purpose of introducing the electrical power domain-specific knowledge graph (DKG) is to make full use of the data information carried by the electrical power Internet of Things to describe the concepts, entities, events, and relationships between them in a structured way, so as to provide a more effective organization, management and cognitive ability of the cross-media bigdata for electrical power industrial chains. Combining with the bigdata and artificial intelligence (AI) technology, domain-specific knowledge graph is gradually becoming one of the core driving forces to promote the development of electric power artificial intelligence. This paper summarized the development process of knowledge engineering in power system, analyzed the development status of knowledge representation, DKG construction and DKG application in China's power enterprises. And according to the data characteristics and development trends of electrical power Internet of Things in China, a so-called NoDKG (i.e. not only domain-specific knowledge graph) based knowledge engineering framework was puts forward. Finally, this paper discussed the application directions and future challenges of DKG technology.