Abstract: The dynamic analysis of the YG-1 cask of 9 m dropping test was performed using the ANSYS/LS-DYNA code. The finite element model was established based on the non-metallic and metallic material parameters obtained from the experiments, and then the primary design of the cask was numerically investigated. The result shows that the steel frame of the cask does not satisfactorily dissipate the shock energy from the dropping heavy plate, which leads to a large stress in the fuel elements and exceeds the stress intensity limitation of ASME BPVC-Ⅲ criterion. Then, a new design of cask was proposed with improvement of the steel frame. The computation for newly-designed cask illustrates that the steel frame can well dissipate the shock energy. Therefore, the entire cask design satisfactorily meets the requirement of ASME criterion.