Abstract: The application of probability methods to earthwork engineering, which is a new subfield in Soil Mechanics, has received increasing attention. This paper is dealing with the probability method of stability analysis for soil slope under the conditions of seepage flow and seismic loading.Based on the conventional calculation fomula of slope stability analysis, the probability model for such analysis has been derived. The expressions of mean and variance of random variables have also been obtained using the First-order second-moment method. The correlations between random variables are discussed rather in detail and the correction coefficient N(MR) as well.Finally, a real case, as an example, is taken to calculate the failure probability using this probability model.