Uniaxial compressive strength, rock quality designation (RQD) and statistics data of joints survey are used as input parameters to construct probabilistic models based on mechanical tests and field surveying data from Muliashi Open Pit. These probabilistic models are well fitted by using the chi-square test. From the generalized Hoek-Brown criterion, the probabilistic distributions of strength and deformation parameters of jointed rock mass are obtained by using the stochastic analysis in the MATLAB program and Monte Carlo method. Spearman’s rank correlation coefficient is applied to analyze the correlations between strength parameters and each input parameters. Based on the practical slope engineering, the slope stability is evaluated from the perspective of failure probability. The proposed method comprehensively considers the uncertainty and variability of jointed rock mass parameters, and can provide a valuable reference for safety decisions of practical engineering projects.