Abstract: The eXtended Finite Element Method (XFEM) is employed to simulate the fracture process of a concrete beam under mixed-mode loading. The cohesive crack model is used to describe the mechanical behavior between the crack surfaces. Tangential retention stiffness is introduced to consider the effects of the shear component. The cracking direction is determined by a simplified maximum tangential stress criterion. The experiments by Arrea and Ingraffea are simulated. The relationship between load and crack mouth sliding displacement (CMSD) predicted numerically agrees well with the experiment results. The results demonstrate that XFEM is an efficient method to simulate the mixed-mode fracture process of quasi-brittle materials because the expression of displacement discontinuities on both sides of cracks is independent of element meshes.