Abstract: Considering the uncertainty of the measurement data, the complexity of determining calculation parameters, the fuzzy character of describing the stability states in the analysis of slope stability, this paper introduces a new method called vertex method that can be used in the stability analysis of slopes. By using this method we can get a fuzzy set of FS (factor of safety) of a slope from some uncertain soil parameters, and then determine the stability states of this slope by a kind of classification method. Finally, a case study is demonstrated to describe the procedure of this method.