Infrared radiation characteristic data is widely used in target infrared characteristic recognition and stealth characteristic evaluation in outfield, and it plays an irreplaceable role in the security and military fields. The acquisition of target infrared radiation characteristic data needs to be based on the system′s radiation calibration. For medium- and long-wave measurement systems, infrared radiation calibration is mainly for fixed-focus systems, but the radiation calibration for zoom systems is less. The model of the infrared radiation calibration was established for the continuous zoom system, and the short-wave continuous zoom system with 1000 mm aperture was analyzed. Data analysis results show that as the F number increases, the radiation response gain of the system decreases. The analysis of its influence on radiation measurement has certain engineering significance.