Abstract: A radiation cooling-based precision thermal control subsystem design is proposed to address the critical thermal management challenge for large-format CCD detectors utilized in total ozone sounding instruments, which are not equipped with thermoelectric cooling (TEC) modules. Given the stringent layout restrictions and unique structural characteristics of the satellite-borne instrument, a dedicated heat dissipation plate with an area of 0.36 m² is specifically engineered for the CCD assembly and mounted on the satellite's +Y side truss. Efficient thermal conduction paths are successfully established through the synergistic utilization of flexible graphite film and heat pipe technology, thereby guaranteeing the low-temperature operation and long-term thermal stability of the CCD sensors. To minimize parasitic heat leakage, polyimide thermal insulation pads are strategically deployed at critical interfaces along the heat transfer path, with equivalent thermal resistances carefully calculated and optimized. At the CCD cold sink interface, an array of multi-channel low-power heaters （2.5 W each, two primary and one backup per channel） is strategically deployed and integrated with advanced proportional-integral-derivative （PID） control algorithms to achieve precise temperature regulation at the millikelvin level. Comprehensive thermal simulation analyses reveal that the CCD chip temperatures across both detection channels can be accurately controlled at −33 ℃ with exceptional stability exceeding ±0.03 ℃, thereby satisfying all technical requirements. The remarkable consistency observed between in-orbit telemetry data and pre-launch thermal modeling results effectively confirms the reliability and predictive accuracy of the thermal design methodology. This innovative thermal engineering approach provides substantial reference value and practical guidance for the development of thermal control solutions for analogous CCD-based detector systems in future space missions.