The problems of the arch structure dynamic buckling subjected to explosive impact are studied by numerical simulation method. The influence of the arch rise span ration on the dynamic response and the dynamic buckling is analyzed mainly. The results show that when the rise span ration of the arch is more than 0.1, the maximum displacement point is the arch top in the elastic vibration stage at about 1/6 of the archspan after plastic deformation occurring. When the impact duration changes in a certain range, the counterintuitive response appears after buckling. There are two corner points in the displacement amplitude vs. load amplitude curve of the arch top. The load corresponding to the first corner point can be seen as the dynamic buckling critical load, and the other corresponding to the second corner point can be seen as the dynamic failure load. When the rise span ration of the arch is less than 0.1, the counterintuitive response doesn't appear after buckling. The dynamic critical load is namely the dynamic failure load. When the impact duration comes to a certain degree, the smaller, the rise span ratio of the arch structure, and the smaller, the dynamic buckling critical load.