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