With the rise of digital media, WeChat official accounts have become important channels for book marketing. This study systematically analyzes the promotion and publicity strategies of the book Why is There a Library in the World via WeChat official accounts and proposes strategic suggestions for cultural institutions utilizing WeChat official accounts for book marketing, this paper selects Why is There a Library in the World as a representative case to explore the related promotional content disseminated through WeChat, mainly using case analysis, investigation research, and network research methods. Specifically, this study first comprehensively investigated the WeChat official accounts involved in promoting this book, and identified a total of 163 WeChat accounts, among which seven accounts demonstrated higher promotional activities, each featuring the book more than twice. These official accounts represent diverse categories, including enterprises, institutions, media, governmental entities, other social organizations, and individual contributors, show a variety of founding subjects, and span across most regions of China. This indicates the impact of the book, reflecting significant attention from different regions and subjects. To evaluate the influence of these official accounts, this paper selects the top 25 tweets and performs a detailed quantitative analysis based on metrics such as readership, likes, and comments (particularly those receiving more than 10 comments). These data not only demonstrate the immediate impact of tweets but also reveal readers' interests and feedback patterns. For example, some highly interactive tweets often included author interviews, book excerpts, or exclusive content, underscoring the importance of providing high-value content in future book marketing. In addition, this paper identifies the reasons why this book is widely praised by carefully browsing tweets on WeChat official accounts and readers' comments and reading through the full text of the book. First, as a distinguished scholar, the uniqueness of the author's professional trajectory and scholarly background significantly augments the credibility of the book's content. Second, the book's ingenious integration of textual ingenuity and visual-aesthetic design has not only elicited readers' intellectual curiosity but also sparked extensive academic discourse. Third, the ingenious combination of the book's Chinese learning and nonfiction writing enables readers to both enjoy the narrative of the story and acquire meaningful insights. Finally, the positive effects of online preheating and media coverage, as well as the social value and cultural significance of this book, have contributed to its broad recognition. On the basis of the above findings, this paper proposes a series of strategies for cultural institutions, including libraries, publishing houses, and bookstores, to optimize their book marketing via WeChat official account. First, innovative content is essential for highlighting the differentiation advantage, attracting the target audience by providing unique content. Second, enhancing interactive features to strengthen reader engagement, and encouraging readers to share personal ideas and experiences can foster an active reader community. Third, developing serialized publications can maintain popularity, maintain public interest through a series of articles on related topics, and prevent the short-term effect of single marketing events. Finally, constructing a media matrix and promoting collaboratively across multiple platforms, by integrating various social media resources can expand overall reach and achieve a wider dissemination effect.