Abstract: In traditional way,water bodies are classified according to the residence time,which is estimated based on the multi-year average flow-through,and the eutrophication sensitivity degrees of lakes reservoirs are evaluated.In this research,in consideration of probability distribution of flow-through,some new hydrodynamic probability parameters,including retention ratio,sluggish flow ratio and back flowing guarantee ratio,are proposed to represent the hydrodynamic futures of water bodies at monthly scale.With these parameters,the identification and classification of eutrophication sensitivity degrees can be established on the basis of considering both seasonal and multi-year variations,and the sensitivity hierarchy has higher resolution.A case study is conducted in the Three Gorges Reservoir,and the hydrodynamic probability parameters in some tributaries are calculated.The results indicate that parameters in different tributaries have obvious differences,and it is necessary to implement distinctive management of eutrophication according to different hydrodynamic conditions.