Abstract: The nonlinear dynamic finite element procedure of ANSYS/LS-DYNA was used and the fluid-solid coupling algorithm was selected to numerically simulate the vertical explosion process of underground arch structures. And the wave theory of p-u Hugoniot curve was adopted to analyze the explosion wave communication process between arch structure and rock. The maximum interaction force and its distribution diagrams of differentspan arch structures were obtained. The results show that the surrounding rock is unloaded and the stress decreases when the wave is travelling from rock with high wave impedance to concrete with low wave impedance. And the surrounding rock is loaded and the stress increases on the contrary. The 40-m-span arch structure as a whole is shocked by tension and comression force when the explosion distance is 5 m and the explosion vibration is evident.