Abstract: According to the membership degree theory of fuzzy mathematics, the fuzzy comprehensive evaluation method transforms the qualitative evaluation into the quantitative evaluation. The result is clear and systematic. It can solve the fuzzy and difficult problems, and it is suitable for solving all kinds of uncertain problems. In this paper, the fuzzy comprehensive evaluation method is used to build the social benefit evaluation index system of power grid engineering, and the weight vector is constructed by AHP to carry out the fuzzy comprehensive evaluation. Finally, the social benefits of specific project cases are evaluated and the conclusion is drawn.