[Purpose/significance] In view of the gap between resource demand and resource acquisition in library service, a flat structure of resource construction model is constructed to help users eliminate the obstacles encountered in the process of using library resources and improve the efficiency of library resource construction.[Method/process] Drawing lessons from B2C business model, this paper probes into the flat design idea of library resource construction. Taking the library resource construction of Chongqing University as an example, it formulates the system of resource construction model and carries out the practical operation of B2C resource construction model.[Result/conclusion] The use of B2C resource construction mode in libraries has significantly improved the collection quality, the efficiency of resource procurement and the satisfaction of resource procurement. There is no intermediate link between library resource demand and user acquisition under B2C resource construction mode. Resource "selection" and "acquisition" are separated. The greatest advantages of both the demander and the purchasing executor are brought into play in resource construction. The paper resources and digital resources purchased by the library are the real needs of users and the resources purchased are purchased. With pertinence, the structure and content of resource construction can be guaranteed optimally.