In the past years, the experts and scholars in the field of library and information in China have always maintained their enthusiasm for the research of information service. The experts and scholars paying close attention to the library development have expanded from the early research on readers to the later research of library information service. The experts and scholars paying attention to the use of information have extended from early user research to the later of human information behavior research. The experts and scholars paying attention to the utilization of information resources have turned the focus from the early information economy research to the later research on information service industry. The experts and scholars paying attention to the basic theoretical issues of information service have been constantly summarizing the research results of the above areas, constantly absorbing and applying the theoretical methods of other disciplines, and striving to create a theoretical system and a discipline of information service science. This chapter mainly introduces the research progress in the field of information service in the past 40 years from the above four aspects.