As the intelligence level grows, a large amount of new knowledge is generated all the time, and knowledge graph has gradually become one of the tools for knowledge management. However, the existing knowledge graph still has some problems, such as missing attributes, sparse relations, and massive noisy information, which leads to poor graph quality and is easy to affect various tasks in the field of natural language processing. As a research hotspot, the knowledge reasoning technology oriented to the knowledge graph is the main method to solve this problem. It improves the information of the knowledge graph by simulating the human reasoning process, with a good performance in many applications. Taking the knowledge graph as the pointcut, this study classifies and explains the knowledge reasoning technology by categories and elaborates on several application tasks of the technology, such as intelligent question-answering and the recommendation system. Finally, it forecasts the main research directions in the future and puts forward several research ideas.