Abstract: Objectives To investigate the dynamic response characteristics of stiffened titanium alloy cylindrical shells under continuous underwater explosion loads, so as to provide a reference for improving the damage capability of underwater combat weapons and the anti-explosion protection design of structures. Methods Firstly, an ALE fluid-structure interaction algorithm is used to establish a numerical model of stiffened titanium alloy cylindrical shells, and the continuous loading of multiple explosion loads is realized by the full restart technology of LS-DYNA. Subsequently, compared with the experimental results, the relative error between the structural deformation calculated by this simulation method and the experimental value is only 6.14%. Finally, the influence of continuous underwater explosion load loading on the structural dynamic response is studied through simulation. Results The analysis of the results shows that affected by the near-field spherical wave effect and cavitation truncation effect, the effective impulse obtained by the structure presents nonlinear characteristics with the increase of the impact factor. Under repeated explosion loading, high-impact-factor loads will cause sudden damage to the structure, and the sharp increase of deformation after the second explosion reflects the weakening of the structural load-bearing capacity by initial defects. The loading sequence has an important influence on the dynamic response of the structure. Applying high-impact-factor loads first can more effectively reduce the structural stiffness and improve the damage effect of subsequent loads. Conclusions The dynamic response of stiffened titanium alloy cylindrical shells under multiple underwater explosions has strong nonlinear characteristics, and the structural damage state is not a linear superposition of each load. The research results can provide a reference for the anti-explosion design of stiffened titanium alloy shells and the damage efficiency design of underwater weapons.