Abstract: The FEM strength reduction technique is used to evaluate a mountainous area substation’s highfill slope’s stability and calculate its potential sliding surfaces which supported by reinforcement structure. The value of FEM calculation parameters are determined by synthesizing the relevant data of insitu tests,soil test and the practice engineering experience. The sliding surface is defined by the though region of plastic strain increment, and then the limit equilibrium analysis method is also used. According to the results, the relationship of horizontal displacement of top of the retaining wall vs the stability safety factor is established, then we found that the results of limit equilibrium analysis is larger than which of FEM, so it is insecurity.