Literature review plays an important role in the writing of master's and doctoral dissertations and is an important chapter in the thesis. The quality of literature review is directly related to the success or failure of the paper. Literature review is the abbreviation of comprehensive literature review, which refers to a systematic and comprehensive description and comment on the research achievements, existing problems and new development trends of the research problems (disciplines and topics) in a certain period on the basis of comprehensively collecting and reading a large number of relevant research documents. "Comprehensive" means collecting the words of "a hundred schools of thought contend" and comprehensively analyzing and sorting them out; "Narration" is to describe and comment on the viewpoints and conclusions of the literature by combining the author's viewpoints and practical experience. Its purpose is not to list the articles that may be found, but to synthesize and evaluate these materials based on their own papers on the basis of determining relevant materials. A successful literature review, with its systematic analysis and evaluation and well-founded trend prediction, can provide strong support and demonstration for the establishment of new topics. I. Function and Purpose of Literature Review Literature review should aim at a certain research topic and explore the current academic achievements. Literature review aims to integrate the information that has been thought and studied in the specific field of this research topic, and systematically display, summarize and comment on the efforts made by authoritative scholars on this topic. Before deciding on the research topic of a paper, we usually pay attention to several questions: how much do we know about this topic in the research field or other fields; What research has been completed; Whether the previous suggestions and countermeasures were successful; Have you suggested new research directions and topics? In short, literature review is the basis of all reasonable research. Most graduate students don't consider these problems, just discuss the literature directly, and simply quote or classify the existing literature found in a short time without criticism. Even has nothing to do with the feasibility and necessity of the paper research. In fact, the purpose of review is to see what exploratory research is, so we should actively expand the sources of research literature. Only in this way can we increase the hypotheses and variables of the study and improve the design of the study. The basic purposes of literature review are at least: to familiarize readers with the progress and predicament of related research in the existing research disciplines; Provide thinking for the follow-up researchers: whether the future research can find more meaningful and meaningful results; To explain the positions of various theories, we can put forward different conceptual frameworks; As the basis of new hypothesis and research idea, the possible explanation of a phenomenon and behavior; Identify the assumptions between concepts and learn how others define and measure key concepts; Improve and criticize the shortcomings of existing research, introduce alternative research, explore new research methods and ways, and verify other related research. In a word, research literature can not only help to determine the research topic, but also find out different views on the research problem. Published research reports and academic papers are important sources of problems, and reviewing papers will provide valuable information and examples of research feasibility. 2. Frequently Asked Questions in Literature Review Literature review can help new researchers to innovate on the basis of existing knowledge, so when writing this chapter, it is necessary to explain to readers the differences between the paper and previous studies. The research on this kind of subject is a new and important academic subject. However, graduate students are prone to make the following four mistakes in the process of writing literature review: 1. A large number of articles are listed and piled up, mistakenly thinking that the purpose of literature review is to show the understanding of other related studies. Therefore, many literature reviews are not centered on the problems studied, but become a list of reading experiences. 2. Give up the right to study and criticize easily. Most colleges and universities in China are students who take the postgraduate entrance examination in our school, so there is often a phenomenon that a large number of research results of their own tutors are cited without paying attention to the research results of other peers. Students are worried that their papers will fail, so they seldom criticize the shortcomings of their tutors' existing research; Students are more likely to give up the right to criticize when they meet famous teachers. As a result of quoting a large number of other people's works, each paragraph begins with who said it. As a result, my paper has become a verification report of the effectiveness of other people's research, and readers cannot believe that my paper has made important contributions. 3. Avoid and abandon research conflicts and find another way. When there are many academic controversial research topics or existing research conclusions are contradictory, some graduate students' papers will avoid contradictions and conduct a research that they think is innovative. Giving up all these conflicts is actually giving up a lot of valuable information, and this so-called innovation, because it has no connection and comparison with any existing research, has no reference value and will be given up by future generations. In the face of uncoordinated or contradictory research, it is found that although it takes more time to deal with it, don't shy away from what is important or even give up on your own initiative. In fact, these disharmonies or conflicts are very valuable and should be used more. It is necessary to integrate the conflicts and contradictions in the existing literature. The new research has better and stronger explanatory power than the old research. One of the reasons is that new research will integrate and improve past gains. 4. selectively explore the literature. Some graduate students do not systematically consult the existing research literature to find out the suitable problems or predictable assumptions, but claim that some research lacks literature, thus admitting that their research is exploratory. If the existing literature is discussed selectively, the literature review will become a reflection of the subjective will of graduate students, which is an opportunistic review. Therefore, it is necessary to conduct a systematic and comprehensive literature review, seek, evaluate and integrate the evidence of scientific research with rigorous scientific design, and ensure the completeness and fairness of the literature review. We should correct the style of study, be brave in exploration and not avoid contradictions. Analyzing the causes, methods and conclusions of the conflict can lay a successful [page_break] foundation for future research and papers, and make the research results of the paper have application value and theoretical significance for subsequent research. Third, the basic methods and steps of literature review. Literature review is not only a summary of a series of irrelevant contents, but also a synthesis of previous research ideas. The basic steps of literature review are: 1. The first step of literature review: there are two main methods to collect literature: one is to search through various retrieval tools, such as literature index, abstract magazine, CD-ROM or network; The second is to extract the relevant literature catalogue from comprehensive articles, monographs, teaching materials and other references. When choosing documents, we should go from near to far, because the latest research often contains the reference materials of previous studies, which can make people know the current situation of knowledge and cognition faster. First of all, we should read the abstract and summary of the literature to determine whether it is related to the research to be done and decide whether it needs to be included in the literature review. Secondly, according to the needs of relevant scientific theories and research, the collected documents are further screened, and the research problems, objectives, methods, achievements and conclusions, as well as existing problems, shortcomings of viewpoints and unanswered questions in each review document are recorded in detail and systematically. Classify related and similar content respectively; For documents with inconsistent conclusions, we should make a comparative analysis and make a judgment of right and wrong according to certain evaluation principles. At the same time, the complete source of each item of information should be indicated, and the secondary information of references should not be ignored, such as publication time, page number and city where the publishing unit is located. Summarize (not repeat) the documents to be reviewed, then analyze, compare and contrast them. The purpose is not to explain the previous studies in detail, but to ensure that readers can understand the main aspects of the previous studies related to this study. It is very important to analyze and comment on the advantages and disadvantages and contributions of previous studies individually and collectively in literature review. 2. Literature Review Step 2: Different disciplines have different requirements and expectations for citation abstracts. Although the literature review is not only a summary, it is necessary to conceptualize and organize the research results. Its methods include: organizing materials and linking them with papers or research issues; Integrate the review results and extract the known and unknown parts; Sorting out the advantages and disadvantages in the literature; The problems to be further studied are put forward. 3. Literature Review Step 3: Criticize whether the literature review is valuable depends not only on the amount of new information and knowledge in it, but also on your own views and opinions on the authors and editors of the literature. When reading literature, we should avoid external influence or even interference, objectively describe and compare the viewpoints, methods, characteristics and achievements of relevant academic schools at home and abroad, and evaluate their advantages and disadvantages. Criticize according to the needs of research, and be careful not to give people the feeling of finding fault. Critical comments must be accurate, self-evident and informative. The degree of criticism is mainly to test the evaluation skills of graduate students: can you analyze the central idea of the article and the arguments put forward, make a summary and make a brief evaluation. The third step of literature review is to formally criticize whether it meets some basic writing standards, that is, to judge whether it is a good article depends on the standards of articles and comments cited in the literature. Some scholars in Taiwan Province Province summarized it as: representativeness, uniqueness, relevance, timeliness and conciseness. 4. Literature Review Step 4: Recommendation 4 Usually, a literature review mainly focuses on comparative comments, analyzing two or more different schools of thought, problems or different positions held by different people. The mode suggested by the University of Hong Kong is shown in Table 1: Table 1 Thesis writing mode suggested by the University of Hong Kong 1. The opening paragraph of introduction: the theme of introduction; The importance of the theme; Clarify the primary problem; Briefly introduce the article and the author (such as A.B.) and their differences or complementarities; 2. Text (3 demos): 1. 1 Analyze the theory/viewpoint of A; 1.2 Analyze B's theory/viewpoint; 1.3 Compare the theories/viewpoints of A and B; 2. 1 Find out the * * * identities of A and B; 2.2 find out the difference between a and b; 2.3 explore a central discussion: topic 1: explore a&; b； Theme 2: Exploring A &；; b； Theme 3: Exploring A &；; B 3。 Conclusion: Put forward a better theory and position than others; As you can see, this model has three options: introduction, text and conclusion. The last step of literature review is to put forward new research directions and suggestions on the basis of review and analysis. According to the development history and current situation at home and abroad, as well as the possible influence of other majors and fields on this major and field, according to the mainstream and laws found in vertical and horizontal comparison, this paper points out several development possibilities, predicts the possible main influences and possible problems, and thus puts forward new research ideas, research contents, suggests specific measures, steps and research schemes, and explains the possibility of results. It should also be pointed out that reading and analyzing the existing literature reviews of other professional researchers can effectively obtain useful opinions and suggestions. However, this comprehensive article focusing on research results can only be used as the basis or reference point for new research, and cannot be used to replace one's own independent research. In short, to do a good job in the topic selection and research of master's and doctoral dissertations, we must pay attention to the overview of materials and write a good literature review.