Abstract: Aiming at the adverse effect on account of pressure failure of breathing apparatus oxygen cylinders, the numerical simulation of cylindrical oxygen cylinder under a certain TNT had been done with the explicit nonlinear dynamic finite element software LS-DYNA, the stress blasting process of oxygen cylinder was analyzed, the speed of element node was obtained when the pressure of oxygen cylinder became invalid and led to blast. The results showed that the plastic instability of oxygen cylinder occurred in the center of the torus, the crack appeared axial dispersion and then the blast happened, the velocity of fragment elements were very fast, which provided the theoretical basis for the explosion-proof device design of oxygen cylinder.