To get social recognition and the basis of development of public libraries in the 21st century, the knowledge information age, Public libraries must recognize their social role clearly and perform it effectively. For performance of advisable social role of public libraries, this study proposed that 1) establishment Library's Bill of Rights, 2) abolition of the function of‘reading room’of libraries, 3) reform of the assessment system and introduction of certification system for improvement in service quality, 4) an epoch-making improvement of library collections.