Paper duplication checking refers to copying and comparing the text of the paper to detect whether there are plagiarism, repetition and omission in the paper. This test mainly compares the databases of major papers, such as CNKI, VIP, PaperFree and so on. To determine whether there is something highly similar to other documents in the paper and its proportion in the total text reproduction ratio. The main purpose of paper duplication checking is to avoid academic misconduct and ensure the integrity and quality of academic research. In the field of academic research, paper duplicate checking has become a normal work, which is widely used in academic evaluation, award selection, degree awarding and so on.