The Siku quanshu, or Complete Library of the Four Treasuries, is the most comprehensive collectanea in Chinese history. In the reign of the Qianlong emperor (r. 1736–1795), the Qing court summoned the realm’s eminent scholars to work on this project; it took decades to finish. The Siku quanshu contains 10,254 works, including some consisting solely of a book title; the collectanea is composed of 172,869 juan (fascicles). The work contains two parts: the first consists of 3,461 collected works, totaling 79,309 juan; the second consists of book titles only, no texts. Although these book titles, without accompanying text, may not seem valuable to some, they are still quite significant and worthwhile. The second part includes 6.793 titles in 93,551 juan.

The Siku quanshu was compiled during the height of the Qianlong era, a time when society was relatively stable and prosperous and the emperor created a desirable social environment and undertook extensive cultural projects. Compiling the Siku quanshu was an enormous undertaking of an unprecedented scale. The Qing court constructed special buildings just to house the project and recruited numerous renowned scholars with specialized knowledge to serve as compilers. Books were successively collected from across the realm, including from private collectors and imperial libraries. Some volumes of the precious Yongle dadian (Great compendium of the Yongle era) were also used.  All of these books were moved to the Siku Institute where they were examined, selected, and compiled into the project. A considerable amount of manpower and resources were expended by the Qing court to facilitate this project. Seven copies were made of the finished collectanea and each was stored in a different library.        

The Siku quanshu is all-inclusive and has been compared to rivers emptying into the sea. It contains more than 3,500 categories of books—the greatest number of any collectanea in Chinese history.  Some of these categories are: classics, history, philosophy, literature, and specialized disciplines of traditional Chinese academic culture. The texts range from the pre-Qin era to just before the Qianlong reign. It includes every major work of the preceding two-thousand years. The Siku quanshu includes not only the works of Chinese authors but also those of different ethnicities, women, and foreign literati.

Two catalogues were produced for the Siku quanshu: one is general and covers the complete work, the other is abridged. The Siku quanshu zongmu (general catalogue) is organized around a traditional classification system that divided all works into four libraries, or branches. These are: Classics (jing), History (shi), Master (zi), and Belles Lettres (ji). Each library is further classified into forty-four categories (lei) which, in turn, are divided into sixty-six subcategories (zimu). The Siku quanshu jianming mulu (Abridged catalogue of the Siku quanshu) is smaller (only twenty juan) and is much more convenient and quicker for finding information.

The Qianlong emperor ordered the construction of four buildings to house the work. These were built in the Inner Court (of the Forbidden City) and in imperial gardens; the design was modeled after the most famous private library in the Ming dynasty (1368–1644)—the Tianyi Pavilion in Ningbo, Zhejiang. Later, the emperor order three more sets of the Siku quanshu to be copied and the construction of three more libraries in Jiangsu and Zhejiang provinces. The four halls, within the Inner Court in the north, and the three halls, in the just-named provinces in the south, became the exclusive locations for housing the Siku quanshu. These libraries played a significant role in the preservation and circulation of this large encyclopedic work.

Many rare books and famous editions (especially those works drawn from the Yongle dadian) are recorded in the Siku quanshu. This was fortunate as few were still extant or in circulation. The Qianlong emperor issued a special edict to choose and print some of the rarest books in order to makes these treasures public again.  These books are known as yingkan (“books that should be printed”).  In Chinese history, the cultural life of the country rises and falls in accordance with the nation’s fortunes. This was no different with the Qing dynasty (1644–1911) and the Siku quanshu suffered a similar fate.

In modern times, China has suffered both domestic turbulence and foreign invasion. The seven sets of the Siku quanshu fell victim to a number of disasters—only three-and-a-half sets are extant. The surviving books are hard to access which makes them inconvenient to use. Beginning in the early twentieth century, some scholars proposed a photolithographic edition. Now, more than a hundred years later, there has been great social, scientific, and technological progress and the proposal has finally been implemented; the undertaking also includes continued revision. This undertaking not only sees a number of ancient books and records better organized, preserved, and used, but it also plays a vital role in carrying forward the legacy of traditional Chinese culture.