The ellipsoidal sliding body is described by using eleven-variable equation

the new version of simplified three-dimensional JANBU method

in which only one variable is used to represent the sliding angles along all the column bases

is presented and is adopted to calculate the safety factor related to given ellipsoidal sliding body; in the case of determining critical sliding body of soil slopes

a new optimization algorithm which takes good advantages of particle swarm optimization and harmony search is presented. Two actual slopes in three dimensions are studied using the proposed method in order to demonstrate the effectiveness and applicability of the proposed method. Comparative studies have shown that the proposed method is applicable to three-dimensional slope stability analysis.