The NLC hosts vast and comprehensive holdings, including extensive collections in foreign languages and many historical books. The NLC's collection totaled more than 44,230,000 volumes and pieces, and this number is increased by nearly one million each year. The NLC's total collection ranked the 7th among national libraries all over the world. Its Chinese collection ranks the first in the world, while foreign languages collection ranks the first in China.

The NLC inherits all royal collections since the Southern Song Dynasty and many celebrities' private collections since Ming and Qing Dynasties. Its oldest collections are the inscriptions on animal bones and tortoise shells (Oracle Bones), which were excavated in Yin Ruins and can be traced back to 3,000 years ago. Valuable and special collections include Dunhuang Manuscripts, western region documents, rare ancient books, epigraphs and rubbings, ancient maps, ancient books in languages of ethnic minorities as well famous expert's manuscripts, totaled more than 3,000,000 volumes and pieces. Dunhuang Manuscripts, the Zhaocheng Tripitaka of the Jin Dynasty, the Yongle Encyclopedia, and the Complete Library of the Four Branches of Literature are considered as the NLC's Four Special Collections.

Adhering to the principle of "Comprehensive collection of Chinese resources, selective collection of foreign language resources", the NLC comprehensively collects all official publications in China. Besides, it pays great attention to collecting unofficial publications in China. It is the collection center of dissertations prescribed by Academic Degree Commission of the State Council, a collector of postdoctoral research reports and materials in library sciences, as well the National Yearbook Collection Center. Moreover, it opens reading rooms for Hong Kong, Macao and Taiwan's publications.

The NLC has been collecting foreign books and periodicals since the 1920s. Documents in 123 foreign languages constitute 40% of the whole collection. In addition, the NLC collects amount of publications of international organizations and foreign governments.

With the development of various new types of information media, the NLC's collection scale is enlarging, and the types are increasing. The NLC has not only collected various microfilms and audio-visual products but also housed a large number of digital resources. It has established the biggest digital resources repository and service base in China. The total capacity of digital resources has been nearly 2757TB, and this number is increased by 100TB each year. The NLC carries out China Memory Project, which collects dictated, video historical data, visual historical data and other new types of literature on major modern events and important figures in China.

Through more than one hundred years of effort, the NLC has established its own characteristic—attaching equal importance to its works of literature collection and utilization. It serves as an all embracing library and a treasure-house of national cultures from the past to the future.