Abstract: Slopes in hydropower engineering are more complicated,higher and steeper than other engineering slopes.Due to the complex geological conditions and large scale man-made activities,the stability of the high slopes has become one of the key problems.A reasonable slope classification system is not only helpful for the description and stability analysis of slopes,but also useful for the geological investigation,design and construction of hydropower projects.Based on the insight of slope classifications in the world and the authors practice experience,the existing specification of slope classification is needed to be modified.A new classification systemic frame is put forwarded in this paper.It takes the hydropower project relationship into consideration and combines the existing schematic achievements.According to the relationship with the project site,the slopes are firstly classified into 2 categories, i.e., dam area slopes and reservoir area slopes.The dam area slopes are further classified into cut slopes and surrounding slopes.Then,slopes are classified 5 ranks according to the importance of hydropower project and the hazards of slopes.Thirdly,it is classified according to characteristics of slope,geometric dimensions of slope,deformation or failure models.Finally,slopes are further classified into different types depending on the lithology,slope structure,inclination angle of slopes,height of slopes,deformation mechanism,failure mode and hazard resources.It is suggested that very steep slopes and hang slopes are divided by 60of inclination angle.High slopes and extra high slopes are divided by 80m of slope heights.The surrounding slopes are classified by the hazard resources.It is found that to use slope mass structure for slope classification is better than to use rock mass structure because slope mass structure is related with the slope stability.