The East Building of Shanghai Library is a key construction project of cultural facilities in Shanghai. With a total construction area of 114, 951 square meters, it is the largest single building of library in the China. The functional space layout of the library is complex, experience requirements are high, thus it's difficult to design. The east library adopts a unique large-span cantilevered steel structure, which is difficult to construct. During the operation period, the annual reception of readers can reach 4 million person-times. The mechanical and electrical systems such as the book sorting system are highly specialized and energy consumption. Under the background of epidemic and carbon peaking, the operation is extremely difficult. The traditional construction and operation model has been unable to meet the demand, so the library proposed to build a smart library based on BIM. However, there is no precedent in China to build a smart library. which achieves the cross-stage model transfer and data merge from design, construction to operation and maintenance. As the general contractor of the east library, Shanghai Construction No.4(Group) Co., Ltd. developed a building industry internet platform, with a series of BIM review, transformation, delivery and big data analysis algorithms, effectively supporting the BIM application of the east library. The application of BIM has improved the construction quality and improved the efficiency of operation and maintenance.