Established in 1957, the collection of the Institute Library is of international significance, with exceptionally rich holdings of books and journals on the history of science and technology in China, and related fields. At present, the Library has more than 170,000 books, including more than 3800 kinds of thread-bound Chinese works (almost 25,000 volumes), and more than 100,000 Chinese books and periodicals as well as more than 50000 foreign books and periodicals. The pride of the Library is the extremely valuable collection of pre-modern Chinese mathematical books donated by LI Yan, the first Director of IHNS. The Library also possesses many large collectaneous reprints of pre-modern Chinese books, such as the Siku Quanshu (“Complete Library of the Four Branches”) and its recently-published supplements, as well as rare and excellent editions of the Confucian classics, history, astronomy, medicine, local gazetteers, etc. It even holds several Dunhuang manuscripts dating from the Tang dynasty.The Library also has some Western scientific books dating back to the early 17th century, and probably the finest collection in China of foreign publications on the history of S&T, including a complete series of ISIS and Landmarks of Science, presented as a gift by the Max Planck Institute for the History of Science.