Abstract: This paper, based on the problems of subject indexing of bibliographic data in the Republic Era, analyzes the most difficult indexing of publication status and content features. Combining with the examples of typical indexing, it sums up the indexing methods to improve the accuracy and efficiency, and proposes that the only way to improve the quality is to encourage the indexers to continue to learn, practice, communicate and exchange.

Key words: Books of Republic Era, Analysis of books, Subject indexing