Abstract: The leakage problems of several typical sections of Gaoshuihe embankment are studied by applying the environmental isotopes method in the paper. The leakage sources of groundwater are ascertained. The result shows that the groundwater of T1^# borehole at Jiangdu dockyard and T23^# borehole at Xiaocaitan section is recharged by the river water,the water of Heiyu-tang around T5^# borehole is recharged by the local precipitation,and the groundwater of T7^# borehole at Wanshougong section is the mixing of river water and local precipitation. Because the environmental isotopes method can only qualitatively explain the problem,the paper attempts to perform quantitative analysis of fuzzy clustering by applying the fuzzy clustering method that the environmental isotope and the hydrochemistry values are taken as the index characteristic values and endued different weightings. The analysis result is according to the conclusion judged by environmental isotope and the hydrochemistry.