This paper focuses on the blast impulse characters of high explosive charge with reactive metal casing. Explosive driving experiments were carried out for high explosive charge with different thicknesses of reactive metal casings and traditional 2 A12 aluminum alloy casings. The power of charge with the two casings was evaluated by analyzing the deformation of 0.3 mm thick Q235 steel foil under the action of the shock wave. Based on the principle of energy conservation, the deflection calculation model of steel foil under explosion load was established. The maximum deflection of plastic deformation of steel foil at different distances under the action of explosive loading caused by the charge with different material casing was calculated. The characteristics of the steel foil damaged by the explosion shock wave generated by the charge with a reactive metal casing were analyzed and compared with the blast impulse of the charge with the traditional 2 A12 aluminum alloy casing. The results show that, with the increase of the thickness of the reactive metal casing, the maximum deflection of the plastic deformation of the steel foil increased, that is, the damage effect to the target improved. The theoretical model of the maximum deflection of plastic deformation of steel foil under explosive loading can accurately predict the deflection of steel foil under explosive loading, and provide a theoretical basis for evaluating the damage effect of reactive materials driven by the explosion. The experimental results showed that the reactive metal casing has a good application prospect in realizing high‐efficiency damage.