Abstract: The reactivity feedback effect of metal burst reactors is driven by the thermal expansion of fuel. The inertia effect on metal burst reactors is caused by delay of reactivity feedback when the material expansion cannot respond to rapid heating changes in time from power excursions. We simulated vibrations by ANSYS under sudden thermal loading, and we calculated quench coefficient on metal burst reactors by stochastic neutron transport program at the same time. After introducing the reactivity feedback behaviors with vibration into the equations of point reactor kinetics, we obtained waveforms of fission pulses in consideration of inertia effect by numerical calculations, and the waveforms are in agreement with experiment results of Godiva. There is a quantitative relationship between the reactor periods and the inertia effect through numerical calculations, and the inertia effect is obvious when reactor periods are narrow.