Abstract: Liquid hydrogen has significant advantages such as high hydrogen storage density, making hydrogen liquefaction technology one of the key technologies for the scaled application of hydrogen. A hydrogen expansion refrigeration and liquefaction cycle process based on the dual-pressure Claude cycle is constructed, and the accuracy of physical property data is ensured by calling the Refprop library. Using genetic algorithms with the specific power consumption as the optimization objective, the thermodynamic parameter design and optimization of the hydrogen liquefaction process are carried out. The hydrogen liquefaction rate of the optimized process is 6.5 t/d, the para-hydrogen content of liquid hydrogen product is 95%, and the total specific power consumption is 10.53 kW·h/kg. The exergy efficiency of the optimized process is 35.72%. The distribution of exergy losses and the proportion of exergy losses in each component of the low-temperature section (excluding the compressor and water cooler) are further provided. The results can provide a reference for the development of large-scale industrial-grade hydrogen liquefaction plants.