Compared with other journals, qualified core journals have stricter requirements on repetition rate. The repetition rate of most core journals is not higher than 10%, some are not higher than 5%, and most general journals are not higher than 25% or 30%. It can be seen that core journals have high requirements for originality and academic content of papers, and it is natural that some participants will check the repetition rate themselves before submitting their papers. Generally speaking, as long as the author writes his own paper carefully, the repetition rate will not exceed 5%. The repetition rate exceeding 10% can only show that there are too many things quoted from others and too few things summarized by himself.