Abstract: With the accelerated evolution of the century-long transformation, the resilience of China's relations with the Global South has sparked extensive debate. Focusing on cooperative practices, mainstream international relations (IR) theories fail to adequately grasp the scientific implication of the statement that "China has always been a member of the 'Global South'", necessitating a "solidarity turn" in IR theories. The analytical framework of international composite solidarity, with affective identification and international division of labor as core variables, reveals the synergistic effects of political consistency and economic complementarity. In the new era, China fosters affective community through relational practices such as summit diplomacy, people-to-people diplomacy, and mutual learning among civilizations. It also promotes interest community through material practices including development cooperation, connectivity, and international institutional reform, advancing the rationalization of division of labor and balanced interdependence among Global South countries within the world system. This composite solidarity mechanism has increasingly become a defining feature of China's diplomacy toward the Global South in the new era, inspiring the construction of a community with a shared future for mankind.