Carrying out social education is one of the functions of public libraries, but "social education" is not a professional term within the scope of library science, and has no clear connotation and extension. This has also caused different scholars to give different answers to the proposition that "libraries carry out social education". Although their arguments are all about "social education", the meaning of "social education" is quite different. According to the current research, social education in public libraries has four different connotations. One is that from the historical development of public libraries in China, the "social education function" of public libraries is to enlighten people's wisdom and improve their quality. This "social education function" is closely related to the social politics of modern China. China experienced ups and downs in modern times and was frequently invaded by foreign countries. Therefore, some enlightened people hope to enlighten people's wisdom and arouse national awakening by learning from the West. The library in China has also experienced the Westernization Movement, the Reform and Reform, the Republic of China reform and other political activities, and completed the transformation from the traditional library to the modern library [1]. This "social education functional school" interprets the "social education function" of public libraries as "opening people's wisdom and improving the cultural quality of the whole people", so it holds a positive attitude towards public libraries to carry out social education and thinks it is necessary for public libraries to strengthen this function. One is from the perspective of analogy with school education that the "social education function" of public libraries is to provide equal and free lifelong education to the public [2]. This school thinks that social education in public libraries is a supplement to school education. On the one hand, school education belongs to stage education, and the public must rely on social and cultural institutions if they want to get the opportunity of continuing education after completing school education. Therefore, public libraries are defined as "social universities". On the other hand, unlike school education, public libraries adhere to a concept of publicity, equality and free, which is different from limited school education to some extent. After all, China still needs a certain threshold to fully realize school education (personal financial resources, educational resources and other factors often cause educational inequality). Therefore, this "social education functional school" interprets "social education function" as "providing equal free education opportunities and lifelong education opportunities to the public" and thinks that social education in public libraries is an important supplement to school education and indispensable. Thirdly, from the perspective of freedom of knowledge and freedom of choice, it is considered that the social education function of public libraries is a contradiction with the freedom of knowledge advocated by them, and there is a trade-off relationship [3]. This school thinks that the social education of public libraries is actually that libraries deprive users of the right to choose information freely. Choosing and controlling the information provided to users is actually to cultivate members needed by society. Starting from the connotation of "education" itself, this school extends the connotation of social education carried out by public libraries. This "social education function school" interprets "social education function" as "selecting and controlling the information provided to users to achieve a certain political and social purpose", so it is very important for public libraries to fulfill "social education function". Fourthly, from the perspective of cultural services of public libraries, the educational function of public libraries is that public libraries can effectively participate in social and cultural activities, and the connotation of "social education function" is extended to libraries to fulfill their social responsibilities. Scholars of this school regard all the activities of public libraries as a part of the social public cultural education organization, and should strengthen their understanding of the public welfare principle of contemporary libraries [4]. This kind of "social education function school" defines "social education function" as "public library's cultural service function of realizing public welfare, including providing all kinds of cultural information to the society, carrying out cultural activities and imparting knowledge to the public". Therefore, they emphasize that the social education function of public libraries should achieve the purpose of developing social culture by enriching their content forms. From the above analysis, it can be seen that the starting point and standpoint of public library's social education function are different, and the conclusions and demonstration methods will be completely different. There is no clear and unified understanding of what is the social education function of public libraries. However, the author believes that it is very important to define the functions of the library in order to develop its services. If the "social education function" of public libraries can't form a standard term with stable connotation and extension, scholars will have different opinions when discussing, and academic debates will easily fall into a strange circle without crossing and collision. References: [1] Fan Yuhong. Social Education Consciousness of Modern Library Construction in China [J]. Library, 2005(4): 13- 16. [2] Zhou. Research on Social Education Service Strategy of Public Library [J]. Library Forum, 2008,28 (5):106-108. [3] Qiu. Knowledge Freedom and Social Education Responsibility of Libraries [J]. journal of library science in china, 2006(4):28-33. [4] Wang. Re-understanding of the social education function of contemporary libraries [J]. Library Forum.