Abstract: An improved method for deriving micromodulus in the prototype microelastic brittle (PMB) material of peridynamics (PD) is proposed to remove the "skin effect" of the original PMB model, and then the failure process of a single-edged notched concrete beam subjected to impact loading is simulated by the improved PMB model. The crack propagation angle, trajectory and the maximum crack growth speed in the mixed-mode fracture can be achieved from PD simulation. The results predicted by PD are compared with those of experiments and other numerical methods to verify the accurateness of the improved model. As an effective method in solving impact problems of structures, PD does not have the element size sensitivity when used to simulate the failure process and contains the description of fracture and damage in its constitutive models.