In order to eliminate the accumulative probability errors resulting from using indirect variables in the Hoek-Brown criterion, the equivalent Mohr-Coulomb parameter probabilities were estimated directly from its basic variables. On the basis of a brief introduction of the Hoek-Brown criterion, the Rosenblueth point estimate and Monte-Carlo methods were selected to calculate the equivalent Mohr-Coulomb parameter probabilities of rock mass for a slope and the reliability index and failure probability of slope stability by two different methods as well. Although only a little difference existed in the computational results calculated by the two methods, but only a small amount of calculations are needed in the Rosenblueth point estimate method. Because the Rosenblueth point estimate method is simple, it can be used to estimate parameter probability, stability reliability and failure probability related to rock mass in engineering.
