Abstract: In this paper, it begins with fundamental concept of seepage force and points out the questions existing in the usual method of slices for stability analysis. Then the finite element method directly applied to stability analysis of earth dams under seepage flow is proposed and the computation formulas for sliding surfaces of single arc and composite arcs are given.In order to justify this method and its computer program we have computed six actual earth dams and two model dams that had occured slope sliding with certain hydraulic condition. The results of computation have verified that those dams should be failed and the most dangerous sliding positions as well as the hydraulic conditions are almost same with that occured in actual dams. On the other side, the computation results by the usual method of slices could not completely verify what the failure in actual cases must be happen. Thus this F. E. M. has been proved that it is more reliable and simpler than others.