Abstract: To reasonably describe the reaction evolution behavior of explosives after ignition under mechanical confinement, conduct in-depth analysis of the deformation and movement characteristics of the shell, and divide the response change process of the shell into three stages: plastic stage, complete yield stage, and inertial motion constraint after shell rupture stage. Considering the coupled effects of combustion crack networks reaction evolution and deformation motion of shell, a model for explosives reaction evolution is established to characterize the inertial confinement effects of the casing movement. This model and parameters are verified by comparing the calculated results with typical experimental data. It is found that the movement velocity of shell and the changes in internal pressure fundamentally indicative the relationship between the energy release of the explosives and the work done by the product gas. Considering the inertial confinement effects of shell motion can more comprehensively characterize the evolution process of explosives reaction, By using this model, the internal pressure of the shell, reaction rate and reaction degree of solid explosives can be calculated based on the historical changes in its movement velocity of the shell, thus providing a theoretical method for the the explosive safety design and evaluation under unexpected stimuli.