According to the definition of the damage variable basing on the stress wave attenuation, this paper makes an expansion to the original numerical manifold program which can only be used to simulate the body deformation of the linear elastic constitutive under the invariable load by adopting the stress wave attenuation damage model. The damage evolution law in the one-dimensional rock long bar under the impact load is simulated with the expanded program, and the damage evolution curves of the different points and the total material are obtained. The simulation results show that the increase of damage mainly happens in the initial time of the impact load, and with the time going on, the intensity of the stress wave attenuates and the damage do not increase evidently.