The cargo containment system of a liquid hydrogen carrier operates at extremely low temperatures, and the hull structures are also exposed to such low temperatures, resulting in a significant temperature gradient. This temperature gradient poses a threat to the safety of both the cargo containment system and the hull structure. This study conducts a temperature field analysis of the hull structure and cargo containment system of a 40 000 m³ liquid hydrogen carrier. The computational fluid dynamics (CFD) method is adopted, considering thermal conduction, thermal convection, and thermal radiation, as well as the thermal coupling effect of the hull structure. A partial cargo hold model is adopted for analysis, which properly reflects the structural arrangement of the cargo hold area and the cargo containment system. The temperature distribution in the cargo holds is analyzed based on the IGC (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk) and USCG (United States Coast Guard) load cases. The results provide a reference for the design of similar vessels.