Considering the randomness of stability analysis of slope and the need of its global analysis ,based on the collected example data of the slope stability analyses, the safety coefficients have been calculated by the maximum likelihood estimation and the general multivariate regression, and the estimation model of slope stability has been established. Then, the safety coefficients of practical slopes have been estimated, and compared with the data obtained from convention monitoring. The results shows that the safety coefficients calculated by the above two method are approach to the monitored results.