Public library is one of the important institutions in public cultural service system. Its development is linked to basic cultural rights and interests of the people and the construction of modern public cultural service system. Owing to the strong support of government，public libraries have been developing rapidly and have got great achievements both in venue construction and service level improvement. However，there are still several problem remaining to be solved，such as the development is uneven and the specialization level is low. This paper takes Shandong Library as an example，combining construction requirements of modern public cultural service system and the current situation of public library’s service efficiency，points out improvement directions of public library’s service efficiency in the new era.