Abstract: Not all of seepage flow is reservoir leakage, so finding out the cause for leakage is important to take effective measures of seepage control. In this paper, a method of relation analysis to investigate and ascertain cause for leakage in embankment dams is put forward, according to this method the cause of leakage can be determined by calculating relation coefficient of seepage discharge to reservoir level or rainfall. Case study shows that this method of relation analysis proposed by this paper is simple and reliable.?