Ecological and environmental issues have always been the focus of government work. The economic losses caused by air pollution, water pollution, noise pollution and solid waste pollution caused by land use development projects are estimated, and the total population economic losses are incorporated into project costing. Using the analytic hierarchy process, four benefit indicators and five cost indicators are selected for constructing a fuzzy comprehensive evaluation model to evaluate the cost-benefit of projects of different scales. The projects of different scales are ranked according to the level of comprehensive scores. The results show that large-scale projects are cost-effective and stable over the long term, and there are differences in the main sources of pollution-caused economic losses for projects of different scales. At last, reasonable policy suggestions are made to relevant planning and management personnel.