Abstract: The crack is cohesive when fracture failure occurs in concrete structures. The discretized equations for simulating the propagation of cohesive crack in concrete structures are built using sub-domain boundary element method. Using this method, the fracture failure process of notched three-point bending beams is analyzed, and the relationship between the applied loads and the deflections is then obtained. The critical load at the unstable fracture point of the concrete beams is determined. Additionally, the double-K parameters, the so-called initial fracture toughness and unstable fracture toughness which are used to judge the fracture process of concrete structures, are calculated based on the crack mouth opening displacement (CMOD) obtained from sub-domain boundary element method. A comparison with the experimental results demonstrates that the sub-domain boundary element method can yield results agreeable well with the experimentally measured results. Thus, it can be concluded that the presented method is accurate and reliable in the analysis of the fracture process of concrete structures.