Abstract: Large liquid hydrogen spherical tanks need to be pre-cooled before they are put into service to avoid damage to the tank structure due to excessive thermal stresses caused by the sudden drop in the internal temperature of the tank. Aiming at the huge cold consumption and high risk of thermal stress in the pre-cooling process, this paper establishes a three-dimensional numerical model of a 2 000 m³ liquid hydrogen spherical tank as the object of study and adopts the CFD method to simulate the pre-cooling process of the spherical tank. The influence of precooling medium type, spray ring structure and outlet position on the precooling process of the spherical tank is analyzed. Based on the study of the spray structure, a new type of double-layer spray ring structure is proposed, compared with the single-layer spray ring structure, and the difference in the pre-cooling effect of the two spray ring structures is analyzed. The results show that compared with the symmetric flow field formed in the liquid hydrogen pre-cooling, the asymmetric flow field formed in the liquid nitrogen pre-cooling can accelerate the cooling of the high temperature region of the wall and inhibit the occurrence of localized overheating phenomenon, and the extreme value of the maximum temperature difference of the wall surface in the liquid nitrogen pre-cooling is only 54.22% of that in the liquid hydrogen pre-cooling. The diameter of the shower ring and the number of nozzles mainly affect the pre-cooling process by changing the distribution of pre-cooling medium and adjusting the nozzle spacing. The new double-layer shower ring structure improves the pre-cooling uniformity by increasing the nozzle spacing through the spatial layering design and reducing the mutual interference between the low-temperature BOGs. The maximum temperature difference at the wall surface during pre-cooling of the new shower ring is reduced by 13% compared with that of the single-layer shower ring.