Prefabricated buildings in water conservancy projects have significant potential in promoting sustainable development, but their complex supply chain structure and synergistic benefits have not yet been fully realized. Existing research primarily focuses on measuring collaborative benefits, lacking a systematic analysis of the driving mechanisms behind synergistic benefits. Based on the resource-based view and institutional theory, this study constructs a synergistic benefit driving model in supply chains from the perspectives of single effects and multi-configuration. Using 648 sample data, structural equation modeling (SEM) and fuzzy set qualitative comparative analysis (fsQCA) are used for empirical research.The results show that resource capacity, financial capacity, technological support, policy support, governance mechanisms, and collaborative culture all significantly promote synergistic benefits, with resource capacity and governance mechanisms playing the most prominent roles. Synergistic benefits arise from the combined effects of multiple factors, forming five typical paths: resource-dominant type, policy-governance driven type, finance-technology collaborative type, culture-technology supportive type, and all-factor balanced type. Therefore, improving synergistic benefits requires differentiated configuration management. Enterprises should select suitable paths based on their specific conditions, promote the deep integration of collaborative culture and technological support, strengthen the synergistic linkage between internal resource endowments and the external institutional environment, and maximize the overall value of the supply chain.

Under the “dual carbon” goal and the high-Iquality development, the limitations of traditional water conservancy project construction models in resource and environmental protection have become increasingly prominent, making the transformation to green construction imperative. Compared with traditional construction methods, prefabricated buildings can significantly reduce energy consumption and carbon emissions, but the complexity of its supply chain links and the diversity of interest subjects result in high operational uncertainties and risks. The grounded theory and PC-ISCOR model are used to identify 29 key drivers of supply chain synergy benefits, and the causal relationship and mechanism of these factors are revealed in depth by constructing the DEMATEL-IISM model, and the Bayesian network model is introduced to further identify the key driving paths. The results show that information sharing rate, organizational structure optimization, multi-Iobjective coordination, resource sharing rate, and feedback speed have a significant positive driving effect on synergy benefits, forming two key driving chains; By optimizing these key indexes, the synergy benefits of the supply chain of prefabricated buildings for hydraulic engineering can be significantly enhanced, thus realizing the enhancement of economic and social benefits.