The aim of sociology of knowledge is to study the interaction between knowledge and the society,and the related elements. The subject is closely related to the course of development of libraries. Therefore,it is feasible and necessary to reexamine the current research paradigm of library history from the perspective of sociology ofknowledge. The emergence and development of modern libraries not only directly reflect the deconstruction and reconstruction of social knowledge system,but also rely on the exertion and enhancement of library functions. Aspractitioners,librarians have been switching between the dual roles of an intellectual and knowledge middle mandue to the demand from changing social knowledge system.