I. Introduction
The structure of this paper is as follows: Section I introduces the background of the recommendation system based on knowledge graph. Section II introduces related knowledge from two aspects of recommendation systems and knowledge graph-based recommender systems. Section III and Section IV classify and sort out the recommendation methods based on knowledge graph in recent years, make tables for reading and searching, discuss and analyze them respectively, summarize the advantages and disadvantages of various methods, and predict the development trend in this field. Section V introduces the application of knowledge graph-based recommendation methods in various fields. Section VI discusses the existing problems and development prospects of recommendation methods based on knowledge graph. Finally, the paper is concluded in Section VII.