[Purpose/significance] Big data has opened a major era transformation of library service. The big data thinking could be used to regard the revolution of library service and have a new understanding of the evolution of its development mode, especially thinking deeply about the pattern, content and mechanism and other different aspects of service in such a new environment.[Method/process] Based on a large number of documents and facts, this paper comprehensively analyzes the evolution process of library service development model from the function perspective of library service and demonstrates the internal logic and external basis of the evolution of library service development model.[Result/conclusion] According to the path of the new format, this paper puts forward two new formats of library service development in data-ages:a new format of knowledge discovery services based on data mining and a new format of innovative application services based on data fusion.