The existing radiation calibration for infrared system with large aperture and broad dynamic range needs huge infrared collimator, but this method has poor motility and cost much. In order to settle this question, a new calibration method basing on the amendment of inner and outer calibration is put forward. This method set a middle-high temperature cavity blackbody in infrared system, with the help of switching reflector, the cavity blackbody radiation is imported into optics system for the inner calibration on parts of system at middle-high temperature range, and an extended source blackbody is needed for the outer calibration on the whole system at middle-low temperature range. The inner and outer calibration data at common temperature range are picked up to calculate the amendatory coefficient. In the end, the whole system′s radiation calibration data at the middle-high temperature range are caught by amending the inner calibration data. Combining the outer calibration data at the middle-low temperature range, the whole system′s radiation calibration data at broad dynamic range are gained. Carrying through this method on an Φ400 mm infrared system and calculating the luminance error and temperature error, the maximal luminance error is 1.35% and the maximal temperature error is 0.76 ℃, the results indicate that the proposed method is effective.