A doctoral thesis is an academic thesis written by a graduate student who is pursuing a doctoral degree. It requires the author, under the guidance of doctoral supervisor, to choose the potential research direction that he can grasp and control and open up new research fields.

It can be seen that this requires the author to have a lot of theoretical knowledge in the professional field of this discipline, and to have in-depth understanding and thinking about the theoretical knowledge of his major. At the same time, you must have a considerable level of independent scientific research ability, and be able to put forward unique opinions and valuable scientific research results in the subject field. Therefore, compared with bachelor's dissertations and master's dissertations, doctoral dissertations have higher academic value and play an important role in promoting the development of disciplines. In order to explore and master the writing rules and characteristics of papers, it is necessary to classify papers. Because the content and nature of the paper itself are different, the research fields, objects, methods and expressions are different, and the classification methods of the paper are also different.

According to the different contents and research methods, the paper can be divided into theoretical papers, experimental papers, descriptive papers and design papers. In addition, there is a comprehensive classification, which divides papers into four categories: thematic, argumentative, comprehensive and comprehensive.