Abstract: The radiative cooling process of oxygen on the lunar surface is critically important for in-situ resource utilization. Different oxygen production methods on the lunar surface may produce oxygen at different initial temperatures and therefore lead to different cooling demands. For different oxygen production methods, this paper analyzes the heat rejection requirements during the initial precooling and pressurization of oxygen under the daytime lunar surface temperature of 127 ℃. The analysis considers both the precooling of oxygen in its initial high-temperature state and the heat rejection required during oxygen collection and pressure increase. Precooling and interstage radiators are designed, and a multi-physics coupled model is developed using COMSOL Multiphysics for the lunar environment where heat dissipation relies solely on radiation without atmospheric convection. The model is adapted to the thermal conditions of the lunar surface and is used to calculate the performance of the radiators under multiple operating scenarios. Multiple simulations of the radiators are carried out, and the results show that the precooling and interstage radiators can effectively cool oxygen from 600 ℃ to 1000 ℃ and 280 ℃ down to 127.12 ℃ and 129.67 ℃ to 130.63 ℃, respectively. Under the design conditions, the precooling radiator meets the cooling requirements for oxygen with initial temperatures ranging from 600 ℃ to 1000 ℃, while the interstage radiator meets the heat rejection requirements during oxygen pressurization. The radiators achieve good temperature uniformity and low pressure drop, which exhibit a sufficient design margin and maintain excellent heat dissipation performance even at five times the design flow rate. Both radiators can therefore maintain effective cooling performance when the oxygen flow rate is increased to five times the design value. This study can provide a reference for gas cooling and handling processes in future lunar in-situ resource utilization.