According to the classification number of China Library Classification, China Library Classification is the most widely used book classification in domestic libraries, which facilitates the classification and retrieval of documents and improves the efficiency of scientific research. The fourth edition of Library Classification of China comprehensively supplements new themes, expands the category system, and makes the classification keep pace with the development of science and technology. At the same time, standardize categories, improve the reference system and annotation system, adjust the category system, and add sub-tables, so as to obviously strengthen the expansion of categories and the accuracy of classification.