The one of the methods which academic libraries maximize the user service is to perform the 'liaison' service that embodies the customized service to make close linkage with library and users. The purpose of this study is to propose the operational plan of 'liaison' service at academic libraries. It was explored the necessity of liaison service, the definition and role of liaison librarian. After this study examined the case of activities and duties of liaison librarian at Korean and foreign academic libraries, the operational plan such as organization, administration and steps et al. of 'liaison' service were proposed.