By using the material of reinforced polyurethane (RPU) foam, the common bulkhead is devised for cryogenic tanks in this paper. Properties of RPU foam are obtained through experiments. Based on the properties, the structure is designed with the integration of special features including lightweight, easy to manufacture, load bearing and thermal insulation. Based on numerical simulation, thermal analysis, stability and thermal mechanical coupling behavior of the structure are analysed. The results show that the common bulkhead not only satisfies the heat insulation requirements of cryogenic tanks for liquid hydrogen and oxygen, but also keeps stability.