Based on Love's shell theory, the critical velocity of a flexural wave in the composite housing of rail-gun barrel is calculated through using the calculation principle of 3-D effective elastic moduli of composite laminate. The result is close to the one predicted by the finite-element method. A 3-D nonlinear transient finite-element model based on the damage mechanics theory and multilayered solid element is established for the filament-wound composite barrel of rail gun under moving electromagnetic pressure. It is used to analyze the dynamic responses and the initiation and development of damage for the rail-gun barrel from the viewpoint of propagation of stress wave. Simulation results reveal that some physical quantities in composite housing for rail-gun barrel, such as stress and displacement, are enlarged obviously with the moving velocity of electromagnetic pressure near the critical velocity of composite housing for rail-gun barrel. Because of the actions of stress waves in barrel, such as reflection, matrix failure occurs first on some axisymmetric planes of composite housing.