This paper adopts the program Ansys and its secondary exploit platform tools to construct three-dimensional model to simulate the destroy process of cave depot. The method that damage surface and yield surface are dealt separately, and dispersion model is forward to simulate flaws. And the results of numerical simulation have been debated to find the laws of flaws growth and distribution with increasing of explosion pressure. It can be found that with the the linear increase of explosion pressure, flaws and distribution regions of flaws grow and expand. Tension flaws are precede to shear flaws. Flaws regions appear in the order , namely, the center of the arch--arch foot-- flaws in the center arch propagation - flaws in other else regions propagation. The research result has important value for online monitor, maintain and reinforce of cave depot. And the technology that has been forwarded in this paper also supplies for the numerical simulation researcher.