The paper expounds the realization principle of mobile identity authentication technology path, takes the usage data of Virtual Private Network(VPN) in the library of Chinese Academy of Medical Sciences as reference and the log data in February 2020 as the sample, compares and analyzes the user access and database utilization of PUMC ID and WebVPN, discusses the issues that should be considered when building mobile identity authentication system in library combined with service effect, so as to provide references for academic libraries to carry out mobile access services.