Abstract: Taking a public library as an example, this paper discusses internal factors and external factors which influence the reader service of public libraries by the method of the key success factors analysis under free-opening background, and determines critical success factors that influence the ？reader services of public libraries by ？ literature research and Delphi technique method, in order to put forward the new research approach based on？？ the combination of qualitative and quantitative analysis for the ？reader service of public libraries.

Key words: public library; free-opening; reader service; Key Success Factors