This study proposed a rough-joint model to simulate the strength and deformability of rock joint under various loadings. The proposed model adopted the Barton model to consider the roughness effect of joint. To implement the rough-joint model in DEM software, three calculation modifications are performed. Afterward, the proposed model was verified by comparing to theoretical model. The comparisons showed that the proposed model is versatile in simulating the shear displacement and shear dilation of joint. Moreover, this study investigated the influence of particle size on the applicability of rough-joint model, and the results indicate that particle sizes have no significant influence on shear behavior, which indicates the rough-joint model is suitable for different scale simulations.