Abstract: Hydrogen energy is an important clean energy that is being vigorously developed. Hydrogen has high requirements for its gas purity during use. With the rapid development of the fuel cell and semiconductor industries, the requirements for hydrogen purity are more stringent, and the general purity requirements are 5N~6N, which poses a greater challenge for the development of efficient hydrogen purification processes. This paper is based on the demand for hydrogen purification with a purity of more than 99% recovered during liquid hydrogen preparation and liquid hydrogen filling in a large-scale hydrogen liquefaction plant. In this paper, four kinds of hydrogen purification processes, such as low temperature adsorption, pressure swing adsorption, palladium alloy diffusion （membrane separation） and metal hydrogen absorption, were compared and analyzed. The adsorption effect of large granular activated carbon on hydrogen and nitrogen in liquid nitrogen temperature region was studied by experiments. At the same time, the purification process of ultra-high purity hydrogen （6N） with more than 99% purity was designed by low temperature adsorption method, and the low temperature adsorption process was modeled, analyzed and optimized by numerical simulation software. The purpose is to explore and develop a large flow, high purity, stable and reliable, economical and efficient ultra-high purity hydrogen purification process suitable for industrial production.