As an imagined community, the Global South is a limited, mutually recognized association based on shared historical memory. Incremental power, common institutions, and identity, in the field of international relations, are the main types of community origins. Nevertheless, they are far from enough to explain the generation and development of the Global South. The historical narrative construction, identity positioning, and Southern discourse articulation emphasize the imagined unity within this collective, yet real differences in internal agency still exist and need to be examined. This article holds that the structure of the system both decides the imaginary boundaries and limits the power distribution of the Global South community, thus forming a power distribution hierarchy. This study identifies four types of agencies generated by preference differences under structural selection and role positioning in the socialization process. They are confrontational suppression, competitive coexistence, cooperative coexistence, and vision-oriented dependence. This categorization is further substantiated through case studies of India, Brazil, Rwanda, and the Shanghai Cooperation Organization, respectively. At present, the Global South community urgently needs to effectively leverage the leadership of major Southern powers, activate the participation effectiveness of small and medium-sized countries and draw on the experiences and institutional models of multilateral cooperative mechanisms. As an essential member of this community, China can help consolidate the Global South community by transcending zero-sum thinking, strengthening institutional resilience, and fostering a stronger sense of shared identity.