Technologies for hydrogen liquefaction have been developing rapidly due to the increasing demand for hydrogen energy. However

hydrogen liquefaction is an industrially complicated process with highenergy consumption and relatively low efficiency. Therefore

many researchers have focused on reducing the energy consumption and efficiency of hydrogen liquefaction. In this paper

recent research and developments in the design and optimization of hydrogen liquefaction are summarized

and the basic and improved hydrogen liquefaction cycles are introduced and compared.The current hydrogen liquefaction process can be divided into two parts: the pre-cooled hydrogen liquefaction process and the cascade hydrogen liquefaction process. The specific energy consumption

exergy efficiencies

and coefficients of performance of these processes are discussed

and the main devices utilized are briefly introduced. Finally

the latest technologies for hydrogen liquefaction and future directions of development are introduced.