Diamond open access (DOA) represents a transformative publishing model that eliminates financial barriers for both readers and authors, positioning itself as a vital counterweight to the increasing commercialization of academic knowledge. Unlike the subscription model, which restricts access behind paywalls, or Gold Open Access, which often shifts the cost burden to authors through Article Processing Charges (APCs), DOA reasserts that research should be a public good. This paper critically examines the inherent conflict between capital-driven interests and the dissemination of knowledge within the global academic framework. By highlighting the stark disparities in academic resource allocation between the Global North and the Global South, this paper elucidates the contemporary inevitability of the emergence of the DOA as a necessary corrective to systemic inequities. Building upon this theoretical foundation, this paper systematically dissects the sustainable development trajectories of DOA across four distinct contexts: Latin America, Africa, Europe, and China. The analysis reveals that these regions have forged markedly different paths, each grounded in unique developmental logic. The Latin American model is characterized by deep regional collaboration and technological sharing, creating a robust infrastructure of collective resilience that operates largely independent of commercial publishers. In contrast, the European model leverages sophisticated top-level design and rigorous standard-setting to construct a high-quality academic ecosystem, ensuring that openness does not come at the expense of excellence. Moreover, despite operating under significant resource constraints, the African model champions a powerful community-driven ethos and a forward-thinking commitment to knowledge equity. These diverse explorations serve as invaluable case studies, demonstrating that there is no “one-size-fits-all” solution to sustainable open access. These international experiences offer profound inspiration for the future of China’s DOA model. The paper argues that the key to China’ s success lies in its ability to synthesize wisdom from these disparate paths to achieve creative transformation and integration. Currently, China’ s DOA landscape faces significant practical obstacles, most notably the fragmentation of its journals and pronounced disciplinary imbalances. To address these challenges, this paper proposes a strategic roadmap that is firmly grounded in national conditions while actively integrating global best practices. Specifically, China should move toward establishing an integrated platform with journal clusters as the primary operational driver, thereby aggregating scattered resources to enhance visibility and impact. Drawing valuable lessons from the European experience, there is a pressing need to establish a "policy-standards-system" trinity of top-level design to ensure quality control and long-term viability. Furthermore, China must uphold an open and inclusive global perspective, ensuring its scholarly output contributes to the world community. By implementing these measures, China can effectively empower the deep-seated reform of its academic publishing system. This approach will ultimately drive the synergistic advancement of both the quantity and quality of China’s DOA journals, fostering a more equitable and dynamic global knowledge ecosystem.