Because of the uncertainty in the parameters of the geometrical discontinuities, there is not a unique solution for evaluating the stability of jointed rock slopes. For this reason, the use of probabilistic methods can be considered suitable. One of the probabilistic methods is using the Discrete Fracture Network-Discrete Element Method (DFN-DEM). Discrete Fracture Network provides real expression of geometrical discontinuities in the ground. This model is based on a random description discontinuities system according to the probability density function of the parameters of discontinuities. Forces acting between blocks using numerical methods such as Discrete Element Method (DEM) can be estimated. The purpose of this study was to develop a probabilistic analysis approach and its related algorithms using DFN-DEM to analyze the stability of jointed rock slopes in different conditions. Statistical Modeling of rock mass discontinuities in three dimensions based on the geometrical parameters of the joints, including the position, size and density per unit volume of rock mass are achieved. Because the joint surfaces are inside the rock mass, they can not measure directly, for this reason it is difficult to obtain size and density of discontinuities in per volume of rock mass. In this study, natural discontinuities of the left abutment Bakhtiari Dam was simulated statistically. In modeling, discontinuities shapes are assumed to be disc. The diameter of joints and their density per unit volume of rock mass with respect to the emprical distribution of measured discontinuities were estimated by theoretical distribution functions. The investigation revealed that the length of the joints is the most fitted to log-normal and power law probability density functions. After establishment of the same size disc, using Watson-William similarities method, the produced DFNs calibrated and the most selected between DFNs field experiments. After determining the geometrical parameters and statistical distribution of joints, DEM method was utilised in produced DFNs with DFN-DEM approach, to assess the slope behaviour. According to history of geology, tectonic evolution in the study area and in situ tests, in situ stresses of the rock mass were determined at the left abutment slope. to analyse of rock slope stability at the left abutment Bakhtiari Dam, kinematic analysis methods, limit equilibrium analysis and numerical method was used. In assessing the stability with kinematic method, there is not any possibility of toppling failure in left abutment of rock slope. At the middle and upper walls, there is possibility of plane failure under joint set J1. The intersection of joint set J1 and bedding plane creates. Wedge which is possible to slide from geometrical point of view at the middle and upper walls. To assess slope stability with limit equilibrium method, the least safety factor is obtained for plane failure related to joint set J1 at upper wall and the result showed the stability of left abutment wall. In numerical analysis, if was found that the slope needs reinforcement and support requirements, the volume of instable blocks based on permissible displacements of conventional rock bolts defined, and it was found the total volume of blocks in each analysis is a good fit with Weibull distribution function. The rock bolt with 9, 12, 15 meter are chosen for support system and 80% of blocks volume are less than 132, 180, 406 m 3 respectively which must be considered.