Abstract: Periodic impact loads are common in mining and civil engineering. The roadway surrounding rock will produce a large number of cracks in a very short time under periodic impact loads, and rock blocks will be ejected from the roadway surrounding rock in a violent way, causing rockbursts and collapses, etc. The continu um discontinuum method has been developed, which the Lagrangian element method and the discrete element method are combined. The method includes four modules: the stress strain module, the nodal separation module, the solving contact force module and the solving motion equation module. The element distortion and local adaptive damping may lead to inaccurate velocities for ejected elements from a model. To accurately model the phenomenon, the ejected elements are treated as rigid bodies based on the continuum discontinuum method. The present treatment can ensure the rigid body movement of the ejected element without contact, which is achieved by averaging the velocities of nodes and eliminating the stresses of elements. The deformation cracking movement process of the roadway surrounding rock under periodic impact loads is modeled. The size of the model is 40 m×40 m. The model is divided into 160×160 square elements, and the size of the roadway is 6 m×6 m. The left and right sides of the model are transmitting boundaries so that no reflection occurs when the stress wave passes through. A few monitored points are arranged at the roadway roof, and the evolution of their maximum principal stresses in the whole calculation process is presented. The process includes the balanced process of the model before excavation, the balanced process of the model after excavation and the propagation process of stress wave in the model. The following results are obtained. When the stress wave propagates in the model, the horizontal velocities of nodes of ejected elements exhibit an increase, followed by a constant and then a decay. This is more practical than the result that the ejected elements are not treated as rigid bodies, and the maximum principal stresses of most monitored points at the symmetric line between the left and right parts of the roadway roof exhibit an approximately fluctuating increase, followed by a decay until a constant is reached. Before a node separate, the maximum principal stress regularly fluctuates, followed by a sudden and violent fluctuation with a large amplitude. The mechanism of roof cracking is expounded. After the stress wave is introduced into the model, the peaks and troughs of maximum principal stresses at the positions of roof increase with time, and the accumulation of several reflected tensile stress waves continuously elevates the peaks of maximum principal stresses at positions, resulting in cracking. In addition, the effects of frequency on the initial ejected velocity and the number of shear and tensile crack segments are preliminarily analyzed. With an increase of frequency, the averaged initial ejected velocity of each element ejected from the roadway surrounding rock increases, and the number of shear and tensile crack segments decreases.