The work aims to study the demonstration method for protection against brittle fracture in spent fuel transportation cask and verify whether the materials of spent fuel transportation cask can still work normally at −40 ℃ without brittle fracture according to GB 11806 Regulations for the Safe Transport of Radioactive Material and IAEA SSG-26. With some spent fuel transportation cask as an example, the finite element simulation of the drop process was conducted with LS-DYNA to analyze the 9 m free drop impact. The traditional method and the linear elastic fracture mechanics were used to verify the ability of protection against brittle fracture in the transportation cask separately. With respect to the traditional method for the analysis of protection against brittle fracture, the materials selected did not meet the requirements, while the materials analyzed by the linear elastic fracture mechanics met the requirements. Compared to the traditional method for material selection, the analysis conducted by linear elastic fracture mechanics can effectively reduce the margin of anti-brittle fracture design and provide an effective way to expand the material selection range of spent fuel transportation cask.