The social impact of hydraulic engineering is chosen as the research object. By determining the social impact variable, a structural equation model for social impact on hydraulic engineering is established, and the paths of social impact on hydraulic engineering are compared. Taking Fujiang Small Hydropower Station as an example, the results show that Fujiang Small Hydropower Station has a great impact on family structure, human landscape and personal income. These impacts should be paid attention to in the evaluation of hydraulic engineering.