Based on the small-scale irrigation facilities in rural communities, the existing problems in cooperative supply of smal-scale irrigation facilities are analyzed, that is, hard formation of elite farmers, difficult negotiation of farmers' hetergeneous demands and inefficient supply. The social capital and farmer household behavior response mechanism are interoreted from the perspective of social capital in the process of cooperative supply of small-scale irrigation facilities. Finally, the relevant policy recommendations, such as strengthening the construction of social capital, cultivating and developing the rural elite team, building reasonable cost-sharing distribution mechanism, and stregthening construction of the community environment.