Public-private partnerships (PPPs) have been increasingly adopted in China. Sustainability of PPPs has become a priority for a sustainable development of PPPs. Most prior studies focus on sustainable implementation of PPP projects. Few research efforts have been done to examine the impacts of PPPs to sustainability from an external perspective and a more macro geographical scale. Meanwhile, the social aspect of the sustainability of PPPs has not been widely studied. Therefore, this study aims to propose a social sustainability contribution evaluation system (SSCES) for PPPs to evaluate PPPs' contribution to regional social sustainability at the institutional level. An indicator system of the SSCES for PPPs was developed, which included 8 requirements for socially sustainable development and 33 social sustainability indicators. The weights of indicators were determined by using the analytic hierarchy process method. The results indicate that, in the context of China, promoting peopleoriented urbanization in PPPs can help enhance regional social sustainability. This study provides a useful evaluation tool for various stakeholders to evaluate the sustainability of PPPs from an institutional level, especially for local governments to review current PPP polices and make improvements.