Abstract: The infrared radiation calibration method is introduced, and the field calibration of infrared warning equipment is carried out by short range direct extended source method and long distance small source method, and the verification and error analysis are carried out. The results show that the relative calibration error of the method is between 5.67% and 15.73% at the temperature range of 10℃~50℃. The relative calibration errors of the remote small source method at 37 m range from 1.38% to 5.72%, and those at 63m range from 10.34% to 29.66%, indicating that the remote small source method at an appropriate distance is an effective method for field calibration of infrared warning equipment operating in the mode of circular scan.