Abstract: 【Purpose/significance】With the popularization of Internet and smart phone, mobile library has gradually become one of the important sources of information access. The purpose of this study is to explore the factors influencing user participation in mobile li⁃brary community services.【Method/process】This study constructed a model based on uses and gratifications theory (U&G) to explain the causal relationships between user gratifications and user engagement. An online survey and a confirmatory analysis were used to test the theoretical model.【Result/conclusion】Through investigation and data analysis, we validated all the research hypotheses. The results showed that hedonic gratification, technology gratification, utilitarian gratification and social gratification all had significant in⁃fluence on user engagement【Innovation/limitation】It is found that user participation has become a key issue in the development of mo⁃bile library user community. Users construct virtual user community through mobile library to integrate social services. This study pro⁃vides policy enlightenment and theoretical support for the construction of mobile library user community by analyzing the factors affect⁃ing mobile library users.