Abstract: To obtain full information of submarine cable systems, a method for building knowledge graph is needed．A knowledge graph was built here from open web data, and data in two existing knowledge graphs, DBpedia and Geonames．Eight (8) entity types and 7 properties in the ontology of the built knowledge graph were identified, with 1 949 entities and 8 535 triples in the knowledge graph, as well as 2 378 links between the built knowledge graph and DBpedia, Geonames．SPARQL queries were applied to make in-depth analysis of the built knowledge graph．This knowledge graph will provide important technical support for intelligent analysis of the global submarine cables．