China has implemented a large number of major infrastructure projects (MIPs) over the last three decades. Social responsibility management is crucial for MIPs' sustainable development. What is social responsibility of major infrastructure (MIP-SR)? To answer this question, this article proposes the concept and key issues of major infrastructure projects' social responsibility (MIP-SR) and develops a comprehensive conceptual framework for MIP-SR, which covers three dimensions: (i) project life-cycle dynamics; (ii) stakeholder's heterogeneity and (iii) social responsibility interactivity. The three-dimensional framework provides a systematic framework for MIP-SR's academic research and practical implementation, which in turn promotes the sustainable development of MIPs.