Abstract: By solving two-dimensional axisymmetric Navier-Stokes equations in conjunction with the chemistry, a numerical simulation of pulse detonation process induced by flame in the tube with CH4-O2-N2 mixture and the flow field outside was performed, and a detailed chemical mechanism of CH4-O2-N2 system, which included 14 species and 19 element reactions, was involved. The computational results demonstrate the process of the development, steady propagation, degenerating into a shock after the detonation wave went into the flow field outside and complex vortex /shock interactions in the vicinity of the thruster exit. The pressure distribution of axis and the head-end (thrust wall) thrust history were discussed to research and exploit a pulse detonation engine .