1. originality: this is the primary criterion to judge whether a paper is plagiarized. If the contents, viewpoints, data and experimental methods of a paper are original, then the paper will not be considered as plagiarism. On the other hand, if the contents, viewpoints, data and experimental methods of a paper are directly copied from other papers, then this paper may be identified as plagiarism.

2. Citation and reference: When writing a paper, we usually quote other people's research results or refer to other people's research methods. But when quoting and referring, you must indicate the source, otherwise it may be considered plagiarism. In addition, when quoting and referring, don't rely too much on other people's opinions and data, but have your own analysis and thinking.

3. Repetition rate: There are many softwares that can detect the repetition rate of papers. If the repetition rate of a paper is too high, then the paper may be considered plagiarism. Generally speaking, if the repetition rate of a paper exceeds 30%, then the paper may be identified as plagiarism.

4. Format and structure: If the format and structure of a paper are very similar to another paper, then this paper may also be considered plagiarism. For example, if the titles, chapter titles and paragraph structures of two papers are very similar, then the two papers may be identified as plagiarism.

5. Content quality: Even if a paper does not copy other people's research results, if the content quality of this paper is very low, such as unclear opinions, insufficient arguments and chaotic logic, then this paper may be identified as plagiarism. Because this kind of paper is actually copying other people's research methods and ways of thinking, rather than innovating and exploring new knowledge.