In order to solve the problems of low emissivity of the ground calibration blackbody，large differences in radiation characteristics between the far and near fields，the inability of the calibration body to adapt to the calibration of loads with different imaging resolutions，and the inconvenience of setting up and withdrawing from the field when the space-based infrared load carries out radiant temperature measurements of typical geographic targets under the conditions of the outfield，a high emissivity calibration plate and a low emissivity calibration plate are developed. A ground temperature difference type calibration blackbody with high emissivity，uniformity and stability is developed，and high emissivity calibration plates and low emissivity calibration plates are made. A method is proposed to realize the absolute radiation temperature calibration of infrared load based on the double temperature expansion source method，and the relative radiation calibration is realized by the image gray scale transformation of far and near ground field using the high emissivity calibration plate and the low emissivity calibration plate. In order to verify the validity of the method，the radiant temperature data measured by a high-precision radiation thermometer on a typical feature target in the near-field are used as the basis for comparing the present method with the existing method based on a large-size surface-source blackbody for realizing in-situ radiant calibration，and the evaluation of the measurement uncertainty is carried out. The results show that the maximum deviation of the radiant temperature calibration of this method is 0.31 ℃，and the measurement uncertainty evaluation result is 0.46 ℃（k=2），which is a good calibration accuracy. Meanwhile，the calibration plate has the features of customizable size，flexible deployment and withdrawal，low cost，etc. It can be applied to the on-site radiometric calibration of space-based infrared loads with different imaging resolutions，which can provide certain technical support for the assessment of target stealth effectiveness，infrared simulation modeling，target characterization and other work.