Abstract: The high frequency pulse tube cryocooler which can achieve 4.2 K（liquid helium temperature）has the advantage of low electromagnetic， light weight and small volume. It would be used in the field of THz communication， deep space exploration and space science experiments. At the same time， it is a hot research area in mechanical cryogenic refrigerator. The performance of regenerator materials has a vital influence on the development of cryogenic refrigerator. Based on the two-stage pulse tube cryocooler working at liquid helium temperature which is a independent self-design in our laboratory and the regenerator materials of Gd₂O₂S provided by University of Science and Technology Beijing， the paper shows a series of experiment studies which focus on the regenerator materials of GOS. The result of experiments points out that the regenerator materials of HoCu₂ is better than GOS under current conditions. And the phenomenon is specifically discussed in the paper.