Abstract: Aiming at the difficulty of the fugitive area source intensity accounting in the field of environmental impact assessment of construction projects, a method based on the concentration of CALPUFF model to reverse the fugitive area source intensity was proposed. Taking an industrial park composed of multiple fugitive area sources as the example, the typical pollutant, SO₂ emitted from the park was selected to calculate and verify the source intensity of the fugitive area sources obtained based on this method. The research results showed that the pollutant emitted from the park in this case had a great impact on the surrounding environment, and accorded with the actual situation that the regional pollutants exceed the standard. For the dynamically changing fugitive area source, the CALPUFF model with concentration reverse method was applied, and the calculated grading source intensity could quantitatively describe the variation range of the fugitive area source; the obtained average source intensity was universal and representative. It could quantify the general situation of effect of multiple fugitive unsteady area sources on the surrounding environment. Therefore, it was feasible and reasonable to calculate the fugitive area source intensity based on the CALPUFF with concentration reverse method.