The CityHub project aims to develop a sustainable smart city data hub that provides integrated management/operation of city data generated from city members, the environment and ICT infrastructure, a smart city service infrastructure, and semantic-based intelligent services through open APIs. Through CityHub’s semantic function, data of Smart City is expressed as semantic data through Common Ontology and Semantic Annotation, which are standard-based common languages, and all city data can be connected by storing it in the semantic Triple Store. In addition, it can be used in various services by providing Open Semantic API and LOD (Linked Open Data).