[Purpose/Significance] In the digital-intelligent era, artificial intelligence is becoming more and more integrated into children's learning, reading, creativity, and daily lives. Cultivating children's AI literacy has become an important issue related to educational transformation, digital inclusion, and the development of future-oriented public cultural services. Public libraries, as open and trusted social education institutions, have accumulated rich experience in reading promotion, information literacy education, digital literacy services, makerspace activities, and services for minors. However, their current AI literacy practices for children are still mostly exploratory and fragmented. Compared with school-based AI education and general digital literacy studies, insufficient attention has been paid to how public libraries can transform scattered activities into systematic, sustainable, and child-centered AI literacy services. This study therefore focuses on how public libraries can move from fragmented exploration to systematic practice in cultivating children's AI literacy within the Chinese context. [Method/Process] This study adopts a multi-case comparative analysis approach and follows the logic of "international paradigm comparison - domestic case analysis - localized pathway construction". First, it examines representative international practices and identifies two typical paradigms: the deep integration paradigm and the systematic popularization paradigm. The former emphasizes the integration of intelligent spaces and curriculum design, while the latter highlights age-differentiated services, community participation, and broad accessibility. Second, the study investigates seven public libraries in Beijing, Shanghai, Guangzhou, and Shenzhen. Based on publicly released activity information from March 2025 to March 2026, more than forty AI-literacy-related activities were collected and analyzed. These practices were classified into three types: cognitive enlightenment, skills practice, and ecological support. Third, drawing on the idea of the "library as education" and Piaget's theory of cognitive development, the study identifies problems with current practices and proposes a systematic framework consisting of practical pathways and supporting mechanisms. On this basis, the study further develops practical pathways and safeguards to ensure the sustainability and functionality of cultivating children's AI literacy in public libraries. [Results/Conclusions] The study found that, although they offer useful references, international practices still face common challenges. These challenges include the tension between service depth and universal accessibility, dependence on external resources, and the lack of systematic evaluation. Domestic public libraries have developed diverse explorations, such as AI-themed reading promotion, lectures, immersive experiences, programming courses, robotics activities, competitions, AI assistants, parent-oriented reading groups, and librarian training. Nevertheless, these practices remain "bonsai-like": they are vivid as individual projects but have not yet formed a sustainable educational ecosystem. In response, this study proposes three practical pathways. The spatial pathway aims to build a virtual-physical "intelligent interactive space" integrating reading, technology experience, creative expression, discussion, digital resources, and AI learning support. The content pathway proposes an age-differentiated and modular AI literacy resource system, progressing from AI perception and story-based enlightenment to operational understanding, ethical reflection, and creative problem-solving. The collaborative pathway constructs a library-school-family educational community, with public libraries serving as hubs connecting formal education, family learning, and public cultural services. To support implementation, the study further proposes three mechanisms: empowering librarians' AI literacy and pedagogical guidance capacity, developing age-differentiated evaluation tools, and establishing long-term driving mechanisms through diversified investment, policy support, professional standards, and social participation. Future research may include fieldwork, interviews, longitudinal tracking, and validation of the evaluation scale to test and refine this framework.