Due to the powerful ability of entity relation expression and reasoning, knowledge graph has been widely used in various fields in recent yearsAiming at the problems of many standards and regulations, construction management and operation cost and high threshold for electric energy metering devices, this paper studies and proposes an automatic construction method for the knowledge graph of electric energy metering devices. To solve the problems of nesting entity, semantic fuzziness, and incomplete graph brought by technical specification documents, the paper adopt the named entity recognition method based on candidate entity graph matching, proposes the relationship extraction method based on multi dependency syntax tree fusion, and applies the relationship reasoning method based on concept hierarchy graph fusion.. The reasoning method is verified in the construction of the knowledge graph of the electric energy metering device.Experiments show that the knowledge map constructed by this method has made a significant improvement in the accuracy and scalability of entity recognition, relationship extraction, and relationship reasoning and can significantly reduce the application review threshold and cost of standards in related fields.