The cold shield is an important component in the infrared detector assembly to prevent external stray energy from entering the detector focal plane and to improve the system's response temperature sensitivity to targets. High operation temperature infrared detector is one of the research directions for third-generation infrared photon detectors. At higher operation temperature, the stray light from the cold shield component will generate background radiation noise, causing interference with the imaging of the infrared detector. Researching the influence and suppression of thermal radiation from high operation temperature cold shield component has a certain significance for the development of high operation temperature infrared detector assembly.Based on the Monte Carlo principle, a cold shield model was established using 3D Studio Max (Fig.2). The model information was extracted to write program to calculate the radiation exchange factors of various parts of the cold shield component to the IRFPA, and the noise signal generated by the thermal radiation of the cold shield component on the IRFPA was obtained. During the internal blackening of the cold shield, the relationship between the noise signal generated by the thermal radiation of the cold shield component on the IRFPA and the temperature was investigated. To suppress the thermal radiation from the cold shield component, two schemes of overall reduction in cold shield emissivity and part reduction in cold shield emissivity were studied and compared.When the cold shield is internally blackened, the noise signal generated by the thermal radiation of the cold shield component on the IRFPA at different temperature were calculated (Fig.5, Tab.3). When the temperature is below 200 K, the noise signal slowly increases as the temperature rises; When the temperature is above 200 K, the noise signal rapidly increases as the temperature rises. When the overall emissivity of the cold shield is reduced, the noise signal generated by various stray radiation on the IRFPA at 200 K were calculated (Fig.6-Fig.7). Overall reduction in cold shield emissivity leads to a rapid increase in noise signals from external stray radiation. Similarly, when the part emissivity of the cold shield is reduced, the noise signals generated by various stray radiation on the IRFPA at different temperatures were calculated (Fig.11-Fig.14), and the suppression effect of part reduction in cold shield emissivity on total stray radiation is temperature-dependent.With the given parameters in this study, the calculation and analysis of a certain high operation temperature cold shield component was carried out. If the ratio of the noise signal generated by the thermal radiation from the cold shield and optical filter to the response signals generated by the target thermal radiation is less than 10%, the temperature of the cold shield component must not exceed 196 K. Total reduction in cold shield emissivity can reduce the noise signal generated by the thermal radiation of the cold shield, but it will cause a rapid increase of noise signal from external stray radiation. Part reduction in cold shield emissivity can reduce the noise signals generated by the thermal radiation of the cold shield and slowly increase the noise signal from external stray radiation. The scheme of part reducton in cold shield emissivity has a temperature-dependent effect on the suppression of total stray radiation; When the temperature of the cold shield component is below 203 K, it will increase the noise signal of total stray radiation; When the temperature of the cold shield component is above 203 K, it can reduce the noise signal of total stray radiation.