Abstract: We are in the era of big data nowadays, and it contains great value in the huge data. Knowledge graph plays a key role in implementing machine intelligence. In this paper, we first introduce an overview of the history of knowledge graph and present several well-known existing knowledge graphs. Then we give a survey of the key technologies of knowledges, including knowledge extraction, knowledge integration, and knowledge processing. Finally, we present the applications of knowledge graph in the field of academic information service, discuss the features and usability of academic knowledge graph and give its schema design.