To consider the roughness effect on shear strength and deformation of rock joint, this research proposed a joint model for the discrete element method. The background theory of the proposed model is based on Barton’s shear strength criterion which is widely used to describe non-cohesive joint with roughness. To implement Barton’s criterion in DEM software, three calculation modifications were performed, including exceeded force recapture, contact area equalization, and stiffness adjustment. Through the modifications, the force of each joint contact could be calculated, which reasonably reflect the joint mechanical behavior under different normal stress. Afterward, the proposed model was verified by comparing to the theoretical model. The results indicated that the proposed model rationally describes the shear stiffness influenced by mobilized joint roughness coefficient during the shear process. The comparisons showed that the proposed model is versatile in simulating the shear displacement with loading-unloading-reloading cycles, normal closure, and shear dilation of joint.