Library is an important part of the public cultural service system. Library policy is a major force that can not be ignored. As the carrier of cultural inheritance, library plays an important role in cultivating and practicing core values and promoting civilized practice in the new era. Excavating the theme of the library is the basis for determining the development and service direction of the library. The library policy is facing difficulties such as unclear construction direction and inadequate guidance. Under this background, the research on China's library policy is carried out. With the library as an example, the topic mining and quantitative analysis of library policies in the eastern, central, and western regions of my country from 2011 to 2020 were conducted using the LDA topic model. Meanwhile, the differences between the three regions were investigated. The results demonstrate that: (1) In terms of quantity, policy texts in the eastern region account for more than half of them; (2) Regarding keywords, high-frequency words mainly include culture, openness, and information in the eastern region, numbers, resources, and reading in the central region, and students, teaching, and learning in the western region; (3) The hot topics in the eastern region involve library government affairs, library digital resources, and library service mode, that is, strengthening the construction of library digital resources and improving service level with an open attitude; (4) The hot topics in the central region contain library management, library student training, and library security, suggesting that the aspects of internal management and system security are emphasized to train students and guide the modernization of the library; (5) The hot topic in the western region includes the construction of two libraries in one station for library evaluation management and library procurement, implying to promote library reform from the bottom up and make crucial arrangements for creating a new situation for grass-roots libraries. On this basis, the policy support of government departments for library development in the future should focus on formulating regulations and rules under the Library Law, establishing a dynamic balance between supply and demand, and enhancing exchanges and cooperation between libraries in the east, middle, and west. [ABSTRACT FROM AUTHOR]