To address global carbon reduction and climate governance challenges, the Center for Energy and Environmental Policy Research (CEEP-BIT) at Beijing Institute of Technology developed the Climate Change Integrated Assessment Model Platform (C3IAM) based on the “time–space–efficiency–benefit” coordination theory. The platform achieves bidirectional coupling between Earth system models and socioeconomic systems through embedded and interactive coupling technologies, comprising seven modules, including global energy-environment policy analysis, climate systems, and ecological land use. By integrating multisource data fusion methods, C3IAM resolves spatiotemporal scale inconsistencies across models, enabling dynamic simulations of greenhouse gas emissions, climate losses, and socioeconomic impacts under various development pathways. Its coupling framework balances macropolicy optimization with microlevel behavioral analysis, quantifying mitigation costs and climate adaptation benefits to support global climate negotiations and national policymaking. Through multidimensional interactive optimization, the platform enhances module synergy efficiency, advancing the scientific rigor and decision-making utility of integrated climate change assessments.