Abstract: The influence of charge shape on the deformation law of open-end steel cylinder under internal blast loading was studied by means of numerical simulation and experiment. The dynamic explicit code LS-DYNA and the Johnson Cook model were used to simulate dynamic response of open-end steel cylinder. The numerical model and parameters were verified by comparison with experimental results of residual hoop strain of steel cylinder without concrete reinforcement under different charge mass. The influence of different shapes of charge, such as cuboid, sphere and cylinder, on the plastic deformation of open-end steel cylinder without concrete reinforcement were studied by numerical simulation at charge mass of 200 g. The aspect ratio of charge was changed from 0.25 to 4. The variation laws of overpressure, impulse and hoop strain of outer wall of steel cylinder were obtained. Based on this, the dynamic response of concrete reinforced steel cylinder under different aspect ratio was simulated. Compared with the experimental results, the deformation law was validated. The results show that the deformation of structure is closely related to the shape of charge. The hoop deformation of steel cylinder is larger when the aspect ratio is larger under the explosion of same charge mass. But the deformation will decrease when the aspect ratio is larger than a certain value. The influence of shape of the charge on the deformation of structure should be emphasized in the design process of protective structures.