Abstract: The ultra large cryogenic system is a major supporting equipment in cutting-edge scientific devices and high-tech applications. With the support of key deployment projects of the Chinese Academy of Sciences, the Technical Institute of Physics and Chemistry CAS has carried out process design work for a 5 ton per day large-scale hydrogen liquefaction device. Through data exchange technology, the connection between low-temperature physical properties databases of ortho-hydrogen, para-hydrogen, and equilibrium hydrogen and commercial process simulation software has been solved, and a process design and simulation platform for large-scale hydrogen cryogenic machines has been established. On this basis, with the goal of refrigeration efficiency and the coordination of various subsystems, the basic specifications of key components of the large-scale cryogenic system for 5 ton per day liquid hydrogen production equipment, as well as parameters such as inlet and outlet pressure, temperature, and flow rate, were successfully determined through optimization analysis. This has laid the foundation for further design and optimization of the future hydrogen liquefaction process.