Literature review is a comprehensive introduction to the existing research results of related topics or related fields on the basis of collecting and consulting a large number of related documents after the research topics are determined. The purpose of this paper is to clarify the existing research foundation and remaining research space of this topic, which can not only point out the direction for researchers to further deepen the research of this topic on the basis of fully drawing lessons from previous achievements, but also help readers (or paper reviewers) to clarify the new ideas of this research. Therefore, writing a good literature review plays an important role in the research of the subject. The structure of literature review generally consists of the following parts: (1) paper: A4 paper, printed on one side. (2) Title: No.3 is bold. (3) The title of the text is bold in small four-song style, and the content is bold in small four-song style. (4) The four words of reference are bold in small four-song style, the contents of reference are bold in five-song style, and the format is written with reference to the reference format of graduation thesis. The writing formats of commonly used references are as follows: a. Periodical format: author, article name, periodical name, publication year, volume number (issue number) and starting and ending page numbers; B book format: author, title, edition number (the first edition should be omitted), place of publication: publishing house, year of publication: starting and ending page numbers; C. Collection format: author and title. (6) Page setup. Margins: 2.5cm from top to bottom, left and right; The line spacing is 1.5 times the line spacing; Character distance: standard.