Abstract: To study the mechanical behaviour of bolt tensile failure which may occur in rock bolting, the structural elements of pile in FLAC3D was used to simulate rock bolts. The simulation results were compared with physical experiments, to validate the credibility of the numerical simulation. The control variable method was used to study the influence of grout cohesive force, shear stiffness, internal friction angle and confinement on the load bearing performance of rock bolts. The results showed that the grout cohesive force had an important effect in determining the reinforcement resistance. If the cohesive force was much higher, the rock bolt may rupture after it was loaded. Additionally, with the confining pressure around the rock bolt increasing, the failure mode of the anchorage body will shift from the bond failure at the bolt/grout interface to the tensile rupture of the bolt. Under the high confining pressure, it is easier to generate the tensile rupture of the bolt.