In this digital era academic libraries are already facing their greatest challenges and difficulties with multiple communication channels. For more than a decade, academic libraries have been under the pressure to change its way of operation and management due to constraint of budget and the appearance of online resources. These situations cause the libraries to value their development of resource and the application of library marketing to better service. How to retain and increase users through enhancement of service becomes the great concern of library managers/ librarians. Customer Relationship Management (CRM) is not a tactical or functional approach but a key strategic process. A comprehensive CRM is highlighted with its pillars, characteristics, basic principles, initiatives in libraries, library service, significance, model and 4S, and user satisfaction through evaluating academic libraries in this study.