Abstract：It is first proved that the two performance functions established in terms of Fs－1 and MR－MS are equivalent mathematically regarding definition of slope stability state. Based on the Duncan nonlinear strength mode，simplified Bishop¢s method，central difference，first-order method and the forenamed two performance functions，a new reliability analysis method of slope stability by using nonlinear strength index is presented. By discussing the sensitivity of the reliability index b to nonlinear strength indexes and the influence of correlation of nonlinear strength indexes on b and critical slip surface location，some beneficial conclusions are drawn as follows. (1) The difference of reliability indices of the two performance functions is less than 0.5%；and it is suggested that reliability analysis is implemented by way of MR－MS，since the derivative of performance function can be computed directly. (2) The difference of reliability indices of first-order method and Monte Carlo method is less than 2%，and b increases with the increase of j0 or redution of Δj；moreover，b is more sensitive with respect to j0 than Dj，so it is quite important to determine the parameter of j0 reasonably. (3) When the correlation coefficient between j0 and Dj varies from 0.0 to 1.0，b increases gradually；the maximum fluctuating percentage is 15.67%，while the critical slip surface is migrating toward the slope face；therefore，if the correlation is ignored，the analysis result would be on the safe side. (4) The reliability analysis of slope stability for the Shuangjiangkou rockfill dam shows that the method is reasonable；the mininum reliability indexes and the locations of critical slip surfaces are realistic；and the slope stability reliability meets the criteria.
