In the 1950s, the library circle completed the construction of the new book classification system.Through the research and analysis of this process, it is clear that the construction of this system went through the early exploration period from 1948 to the first half of 1950, the brewing and forming period of the new classification system from the second half of 1950 to 1956, and the birth and development period after 1957.Finally, the "large method" was born, which marked the basic maturity of the unified classification in China.