The work aims to design a transport container for fissionable uranium dioxide powder and prove that the container can meet the design criteria of nuclear criticality, shielding safety and radioactive material containment under a 9 m drop in the most dangerous posture. A three-layer sealed container that was flexible on the outside and rigid on the inside was designed, the vibration-reducing and energy-absorbing polyurethane materials were filled between the inner and outer shells, the dynamic response of the structure and functional materials of the container under various postures was established and analyzed, and the most dangerous dropping posture was determined. An actual drop test was carried out for the most dangerous working conditions to prove the safety of the container under imaginary accidents. Under the most dangerous dropping condition of the container, the vibration-reducing and energy-absorbing effect of polyurethane materials was consistent with the design calculation, and the position and defect amount of functional materials such as neutron absorption plate and neutron moderator plate met the requirements. The tightness of uranium dioxide powder was guaranteed. The container simulation analysis based on finite element analysis has a high matching degree with the prototype test results. The prototype has passed the relevant drop test, proving the safety performance of the container in a dangerous posture under a 9 meter drop.