In order to make an objective and holistic environmental evaluation of hydraulic engineering projects,the Yanshan Reservoir project,which is one of the key projects of Huaihe River harnessing,was taken as an example in this study.Principles and the method of impact scope and degree were analyzed based on the analysis of soil loss impacts on the construction area of the project.A comprehensive evaluation model of the impacts was preliminarily established.It can provide a holistic and quantitative result of impact evaluation for the project.By using this method,some shortcomings by using the single factor analysis method can be overcome.