Abstract: In post-evaluation era，service effectiveness is the focus of public library development.There are three major factors of service effectiveness.The first factor is libraries themselves and their geographic distribution，as that is the basis of service.The second is libarians，as they are providers of service.The third is readers'demand，as it is the gauge of service effectiveness.This article，by analyzing those factors，draws a road map to improving service effectiveness of public library.

Key words: post-evaluation era；public library；service effectiveness