Abstract: Aiming at the problems existing in the ecological environment impact assessment, such as partial evaluation indexes selection and difficulties in determining the standard value, taking Chaohu Lakeside’s regulation projects for flood control as an example. Based on the theory of pressure—state—response model, an evaluation index system was established which took consideration of the characteristics and degree of ecological environment impacts. The weights were determined using the entropy method. In order to enhance the comparability of different evaluation units, selecting grey model to make quantitative evaluation of the ecological environment impacts of Chaohu Lakeside’s regulation projects for flood control during the construction period. The comprehensive index method was used for comparative verification. Results showed that: 1) The approaching degrees of different evaluation units were different, the corresponding eco-environmental quality grades of Feixi County, Baohe District, Feidong County, Chaohu City and Lujiang County were good, good, general, general and poor. 2) Harnessing the waste discharged actively and increasing the input of environmental protection funds could achieve good results for Feixi County where the pressure layer had a higher approaching degree than that of state and response layer. The situation in Baohe District, Feidong County, Chaohu City, Lujiang County was just the opposite, so it would be useful to make reasonable arrangements for the construction site and time to reduce the emission of waste and improve the region’s ecological environment quality.