The database of the duplicate checking system of HowNet includes: the general database of online publishing of academic journals in China; China Doctoral Dissertation Full-text Database/China Excellent Master Dissertation Full-text Database; Full-text database of important conference papers in China; Full-text database of important newspapers in China; China patent full-text database; Internet resources (including forum resources such as post bars); English database (covering English data of journals, doctoral programs and conferences, as well as Springer and Taylor &; Francis periodical database, etc. ); Hong Kong, Macao and Taiwan Academic Literature Library; Give priority to the publication of literature library; Internet literature resources; Book resources; CNKI Dacheng editor-original works library and personal comparison library. From the first point, we can know that there are two unique databases for duplicate checking of HowNet papers-"Joint Comparison Database of College Students' Papers" and "Joint Comparison Database of Academic Papers", which are included in the pmlc system of HowNet undergraduates and the VIP system of HowNet Shuobo respectively.