Abstract: In order to achieve ignition successfully, the thickness uniformity of the ice layer more than 99% and root mean square of the surface roughness less than 1 μm are required in the ICF cryogenic target system. Analytical calculations indicate that a maximum temperature difference of target surface less than 0.1 mK can meet the above ignition requirements. In this paper, a 3D spherical hohlraum cryogenic target model was established to study the influence of radiation on the temperature field of the system. The results show that in comparison with cylindrical target hohlraum, the spherical hohlraum has more uniform temperature distribution due to its spherical geometry. In addition, the temperature of the window-side capsule is higher than the other side due to the external radiation. The higher the radiation temperature is, the higher the absolute temperature of the capsule surface is. To avoid deterioration of the DT ice uniformity, multi-layer shield structure should be used to reduce the influence of the high excessive radiation temperature. When laser sealing film absorption rate is greater than 0.2, the surface temperature of the target significantly increases.