This paper first analyzes the causes of the low utilization ratio of the floating population to the library by the example method; and then from the perspective of reading promotion, it explains the various extension services of the library through cultivating social organization of the floating population, customizing the personalized information service for the floating population, and setting up the library community mobile station. By focusing on the reading and promoting activities of the floating population, the utilization rate of the floating population to the library is greatly promoted, and the public cultural service of the library is enriched and promoted in the practical sense.