On the background of more and more demands for the evaluation of municipal engineering projects, the benefits of municipal engineering are paid more and more attention, and, at present, the research focus in the field of engineering is more on the benefit of single index than comprehensive evaluation benefits, this paper puts forward the concept of "comprehensive benefit" evaluation of municipal engineering based on various indicators of comprehensive engineering benefits. This paper puts forward an evaluation model of comprehensive benefits of municipal projects based on triangular fuzzy number and fuzzy comprehensive evaluation method, which can carry out post evaluation of comprehensive benefits of various municipal projects under various modes such as PPP, BT and BOT. Through example demonstration, it is proved that the evaluation model is scientific, practical and operable, which provides favorable engineering measures for the sustainable development of the city and the construction of a resource-saving and City friendly society.